High refractive index phosphate glass

ABSTRACT

Disclosed herein are glasses that present several advantages over traditional glass compositions used in optical applications. The glasses disclosed herein have a low devitrification tendency and can be processed by melt quenching and formed into macroscopic components. The glasses have high glass thermal stability indices and are chemically durable. The glasses disclosed herein are transparent when heat treated in air or oxygen and have high refractive indices and low density, as well, making them suitable for optical applications.

This application is a continuation of and claims the benefit of priorityto U.S. application Ser. No. 16/700,061, filed on Dec. 2, 2019, whichclaims the benefit of priority to U.S. Provisional Application Ser. No.62/776,668 filed on Dec. 7, 2018, the contents of which are relied uponand incorporated herein by reference in their entirety.

BACKGROUND

The demand of optical glasses with high refractive index (e.g., greaterthan 1.70) and low density has increased with the growing market fordevices used in optical displays for augmented reality devices orvirtual reality devices, optical fibers, and optical lenses. The otherrequirements for these optical glasses are good glass formability,relatively low production cost, and good chemical durability towithstand chemical cleaning and various environmental conditions. Theglass compositions described herein possess desirable properties withrespect to their manufacture and use in optical articles.

SUMMARY

Disclosed herein are glasses that present several advantages overtraditional glass compositions used in optical applications. The glassesdisclosed herein have a low devitrification tendency and can beprocessed by melt quenching and formed into macroscopic components. Theglasses have high stability indices and are chemically durable. Theglasses disclosed herein are transparent when annealed in air or oxygenand have high refractive indices and low density as well, making themsuitable for use in numerous optical articles and applications.

The advantages of the materials, methods, and devices described hereinwill be set forth in part in the description that follows, or may belearned by practice of the aspects described below. The advantagesdescribed below will be realized and attained by means of the elementsand combinations particularly pointed out in the appended claims. It isto be understood that both the foregoing general description and thefollowing detailed description are exemplary and explanatory only andare not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several aspects described below:

FIGS. 1A and 1B show the transmittance of a glass composition heated at660° C. with oxygen purge for 0.5 hour and 1 hour (FIG. 1A) and in airat 640° C. for 1 hour (FIG. 1B) compared to the same glass compositionthat was not heated.

FIG. 2 shows the refractive index of a glass composition that was heatedat 660° C. with oxygen purge for 16 hours compared to the same glassthat was not heated under oxygen.

FIGS. 3A and 3B show that glass compositions that include CeO₂ have ahigher refractive index and transmittance, respectively, compared to aglass composition that does not include CeO₂.

DETAILED DESCRIPTION

Before the present materials, articles, and/or methods are disclosed anddescribed, it is to be understood that the aspects described below arenot limited to specific compounds, synthetic methods, or uses, as suchmay, of course, vary. It is also to be understood that the terminologyused herein is for the purpose of describing particular aspects only andis not intended to be limiting.

In the specification and in the claims that follow, reference will bemade to a number of terms that shall be defined to have the followingmeanings:

It must be noted that, as used in the specification and the appendedclaims, the singular forms “a,” “an,” and “the” include plural referentsunless the context clearly dictates otherwise. Thus, for example,reference to “a metal oxide” in a glass composition includes mixtures oftwo or more metal oxides and the like.

“Optional” or “optionally” means that the subsequently described eventor circumstance can or cannot occur, and that the description includesinstances where the event or circumstance occurs and instances where itdoes not. For example, the glass compositions described herein mayoptionally contain an alkaline earth metal oxide, where the alkalineearth metal oxide may or may not be present.

As used herein, the term “about” is used to provide flexibility to anumerical range endpoint by providing that a given numerical value maybe “a little above” or “a little below” the endpoint without affectingthe desired result. For purposes of the present disclosure, “about”refers to a range extending from 10% below the numerical value to 10%above the numerical value. For example, if the numerical value is 10,“about 10” means between 9 and 11 inclusive of the endpoints 9 and 11.

Throughout this specification, unless the context dictates otherwise,the word “comprise,” or variations such as “comprises” or “comprising,”will be understood to imply the inclusion of a stated element, integer,step, or group of elements, integers, or steps, but not the exclusion ofany other element, integer, step, or group of elements, integers, orsteps.

The “refractive index” of a material is a number that describes howlight propagates through that material. It is defined by the equationn=c/v, where c is the speed of light in a vacuum and v is the speed oflight as it propagates through the material. In one aspect, therefractive indices of the materials disclosed herein show littlevariation over the measured wavelength range and, hence, arecharacterized by low dispersion.

As used herein, the “glass transition temperature” (T_(g)) of a materialcharacterizes the temperature at which the glass transition occurs in anamorphous material. At temperatures below T_(g), the material exists ina hard and brittle state and at temperatures above T_(g), the materialexists in a supercooled liquid state. T_(g) is always lower than themelting temperature of a material's crystalline state, if a crystallinestate exists for the material.

As used herein, “devitrification” is the formation of crystallinestructures in glass. Devitrification can result from improper cleaningof glass surfaces, during cooling of the melt from melting temperatures,from holding the glass at a high temperature for a long time (which maycause crystals to nucleate), or simply from the tendencies of the rawmaterials in the glass. In one aspect, simple binary titanium phosphateglasses have a high devitrification tendency. In a further aspect,devitrification can be avoided by using rapid quenching techniques suchas, for example, roller quenching. In a still further aspect, the glasscompositions disclosed herein have low devitrification tendencies andthus can be quenched to the glassy state using cooling rates that aresubstantially slower than those associated with roller quenching.

As used herein, “glass thermal stability index” refers to thetemperature difference between the onset of crystallization (T_(x)) andthe glass transition (T_(g)) (i.e., T_(x)−T_(g)) as measured bydifferential scanning calorimetry (DSC). The onset crystallizationdetermined by DSC is the onset crystallization peak upon heating of aglass from room temperature to melting temperature at a rate of 10°C./min. Methods for determining the onset of crystallization (T_(x)) areprovided in the Examples. In one aspect, the glass compositionsdescribed herein have a high glass thermal stability index. In a furtheraspect, the glass compositions described herein can have a glass thermalstability index of 100° C. or greater, or 150° C. or greater, or 200° C.or greater. In other aspects, a crystalline state does not exist for theglass composition and the glass thermal stability index is a negativenumber corresponding to −T_(g).

“Dispersion” as used herein is a change in the refractive index of amaterial with wavelength. In one aspect, the glass compositionsdescribed herein have lower dispersion than other high refractive indexglasses such as, for example, glasses containing lead or bismuth.

“Melt quenching” is a common technique for producing glasses. In meltquenching, raw materials are mixed into a batch and melted; the durationand temperature of the melt depend on the melting points of theindividual components. Following melting, the glass can be cast and thenannealed near T_(g) to remove thermal stresses that may remain. Glassesthat have been melt quenched can be further processed by sawing,grinding, polishing, and other techniques. In one aspect, the glasscompositions disclosed herein can be processed via melt quenching. In afurther aspect, the glass compositions disclosed herein can befabricated into macroscopic pieces.

“Roller quenching” is a rapid quenching technique used in the processingof materials with poor glass forming tendencies into glasses. In rollerquenching, the glass melt is poured through rollers. In one aspect, theglass compositions disclosed herein have good glass forming tendenciesand do not need to be processed by roller quenching.

“Annealing” as used herein is the process of slowly cooling hot glassafter the formation of an object from the glass melts as well asreheating the glass from room temperature to annealing point and keep atannealing point for certain time, and then slowly cooling back to roomtemperature. In one aspect, annealing can relieve internal stressesintroduced during the manufacture of a glass object. In another aspect,the glasses described herein can be strongly colored when formed byconventional melting in air, but can be bleached to transparency byannealing in air or oxygen at elevated temperatures, includingtemperatures near T_(g). The “annealing temperature” or “annealingpoint” of glass is the temperature at which the viscosity of the glassreaches 10^(13.2) Poise. In one aspect, at the annealing temperature,the viscosity of the glass is still high enough that the glass canresist external deformation (and any resultant breakage) but becomesjust soft enough to relax internal strains. In one aspect, the annealingpoints of the glasses disclosed herein can range from 450 to 750° C.

A material such as an object formed from a glass composition can changein shape, area, or volume in response to a change in temperature. The“coefficient of thermal expansion” is the degree of expansion divided bythe change in temperature and can vary with temperature. Methods fordetermining the coefficient of thermal expansion are provided in theExamples.

References in the specification and claims to atomic percentages of aparticular element in a composition or article denote the molarrelationship between the element or component and any other elements orcomponents in the composition or article for which an atomic percentageis expressed. Thus, in a composition containing 2 atomic percent ofcomponent X and 5 atomic percent of component Y, X and Y are present ata molar ratio of 2:5, and are present in such a ratio regardless ofwhether additional components are used in the composition.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of any such list should be construedas a de facto equivalent of any other member of the same list basedsolely on its presentation in a common group, without indications to thecontrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range was explicitly recited.As an example, a numerical range of “about 1” to “about 5” should beinterpreted to include not only the explicitly recited values of about 1to about 5, but also to include individual values and sub-ranges withinthe indicated range. Thus, included in this numerical range areindividual values such as 2, 3, and 4, the sub-ranges such as from 1-3,from 2-4, from 3-5, from about 1-about 3, from 1 to about 3, from about1 to 3, etc., as well as 1, 2, 3, 4, and 5, individually. The sameprinciple applies to ranges reciting only one numerical value as aminimum or maximum. Furthermore, such an interpretation should applyregardless of the breadth or range of the characters being described.

Disclosed are materials and components that can be used for, can be usedin conjunction with, can be used in preparation for, or are products ofthe disclosed compositions and methods. These and other materials aredisclosed herein, and it is understood that when combinations, subsets,interactions, groups, etc. of these materials are disclosed, that whilespecific reference to each various individual combination andpermutation of these compounds may not be explicitly disclosed, each isspecifically contemplated and described herein. For example, if analkali metal oxide additive is disclosed and discussed, and a number ofdifferent alkaline earth metal oxide additives are discussed, each andevery combination of alkali metal oxide additive and alkaline earthmetal oxide additive that is possible is specifically contemplatedunless specifically indicated to the contrary. For example, if a classof alkali metal oxides A, B, and C is disclosed, as well as a class ofalkaline earth metal oxide additives D, E, and F, and an examplecombination of A+D is disclosed, then even if each is not individuallyrecited, each is individually and collectively contemplated. Thus, inthis example, each of the combinations A+E, A+F, B+D, B+E, B+F, C+D,C+E, and C+F is specifically contemplated and should be considered fromdisclosure of A, B, ad C; D, E, and F; and the example combination A+D.Likewise, any subset or combination of these is also specificallycontemplated and disclosed. Thus, for example, the sub-group of A+E,B+F, and C+E is specifically contemplated and should be considered fromdisclosure of A, B, and C; D, E, and F; and the example combination ofA+D. This concept applies to all aspects of the disclosure including,but not limited to, steps in methods of making and using the disclosedcompositions. Thus, if there are a variety of additional steps that canbe performed with any specific embodiment or combination of embodimentsof the disclosed methods, each such composition is specificallycontemplated and should be considered disclosed.

The term “R₂O” refers to alkali metal oxide and is used to represent thecombination of all alkali metal oxides in a glass composition. Alkalimetal oxides include Li₂O, Na₂O, K₂O, Rb₂O, and Cs₂O. If only one alkalimetal oxide is present in a composition, R₂O refers to that alkali metaloxide. If two or more alkali metal oxides are present in a composition,R₂O refers to all alkali metal oxides collectively. Reference to amountor concentration of R₂O means the combined amount or concentration ofall (one or more) alkali metal oxides expressed as mol %.

The term “RO” refers to alkaline earth metal oxide and is used torepresent the combination of all alkaline earth metal oxides in a glasscomposition. Alkaline earth metal oxides include MgO, CaO, SrO, and BaO.If only one alkaline earth metal oxide is present in a composition, ROrefers to that alkaline earth metal oxide. If two or more alkaline earthmetal oxides are present in a composition, RO refers to all alkalineearth metal oxides collectively. Reference to amount or concentration ofRO means the combined amount or concentration of all (one or more)alkaline earth metal oxides expressed as mol %.

Unless otherwise specified, amounts or concentrations described hereinfor components in a glass composition refer to mol % of componentsincluded in the glass composition produced herein.

The glass compositions described herein include phosphorous pentoxide(P₂O₅), niobium pentoxide (Nb₂O₅), one or more alkali metal oxides(R₂O), one or more alkaline earth metal oxides (RO), and one or moreoptional glass-forming components. As will be discussed in detail below,by varying the relative amounts of each of these components theproperties of the glass composition can be modified.

The glass compositions described herein contain P₂O₅. In one aspect, theamount of P₂O₅ is from about 20 mol % to about 40 mol %. In anotheraspect, the amount of P₂O₅ is about 20, 25, 30, 35, or 40 mol %, whereany value can be a lower- and upper-endpoint of a range (e.g., 25 mol %to 40 mol %, 25 mol % to 35 mol %, etc.).

The glass compositions described herein contain Nb₂O₅. In one aspect,the amount of Nb₂O₅ is from about 10 mol % to about 50 mol %. In a stillfurther aspect, the Nb₂O₅ is present at about 10, 15, 20, 25, 30, 35,40, 45, or 50 mol %, where any value can be a lower- and upper-endpointof a range (e.g., 15 mol % to 30 mol %, 20 mol % to 30 mol %, etc.). Thepresence of Nb₂O₅ in the glasses described herein contributes to anincrease in refractive index of the glass materials.

The glass compositions described herein contain one or more alkali metaloxides (R₂O), which includes Na₂O, Li₂O, K₂O, or any combinationthereof. In one aspect, the amount of the alkali metal oxide is fromabout 1 mol % to about 35 mol %. In a still further aspect, the alkalimetal oxide is present at about 1, 5, 10, 15, 20, 25, 30, or 35 mol %,where any value can be a lower- and upper-endpoint of a range (e.g., 5mol % to 15 mol %, 5 mol % to 20 mol %, etc.).

In one aspect, the alkali metal oxide is Na₂O in the amount of 1 mol %to 35 mol %. In another aspect, the alkali metal oxide is Li₂O in theamount of 1 mol % to 15 mol %. In another aspect, the alkali metal oxideis K₂O in the amount of 1 mol % to 10 mol %. In the case when a singlealkali metal oxide is present in the glass composition, the amount ofalkali metal oxide is from 1 mol % to 35 mol %. In a further aspect, thealkali metal oxide is Na₂O in the amount of 1 mol % to 35 mol %, Li₂O inthe amount of 1 mol % to 15 mol %, and K₂O in the amount of 1 mol % to10 mol %, where the sum of R₂O is from about 1 mol % to about 35 mol %.

The glass compositions described herein contain one or more alkalineearth metal oxides (RO), which includes CaO, BaO, MgO, SrO, or anycombination thereof. In one aspect, the amount of the alkaline earthmetal oxide is from about 5 mol % to about 40 mol %. In a still furtheraspect, the alkali earth metal oxide is present at about 5, 10, 15, 20,25, 30, 35, or 40 mol %, where any value can be a lower- andupper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 20 mol%, etc.).

In one aspect, the alkaline earth metal oxide is BaO in the amount of 1mol % to 25 mol %. In another aspect, the alkaline earth metal oxide isCaO in the amount of 1 mol % to 20 mol %. In another aspect, thealkaline earth metal oxide is MgO in the amount of 1 mol % to 15 mol %.In another aspect, the alkaline earth metal oxide is SrO in the amountof 1 mol % to 30 mol %. In the case when a single alkaline earth metaloxide is present in the glass composition, the amount of single alkalineearth metal oxide is from 5 mol % to 40 mol %. In a further aspect, thealkaline earth metal oxide is BaO in the amount of 1 mol % to 25 mol %and CaO in the amount of 1 mol % to 20 mol %, where the sum of BaO andCaO is from 1 mol % to 40 mol %. In another aspect, the alkaline earthmetal oxide is BaO in the amount of 1 mol % to 25 mol %, CaO in theamount of 1 mol % to 20 mol %, and SrO in the amount of 1 mol % to 30mol %, where the sum of BaO, CaO, and SrO is from 5 mol % to 40 mol %.

The amount of P₂O₅, alkali metal oxide, and alkaline earth metal oxidecan be varied in order modify the properties of the glass composition.In one aspect, the molar ratio of R₂O/(R₂O+RO) is greater than 0.25. Inanother aspect, the molar ratio of R₂O/(R₂O+RO) is greater than 0.25, or0.5, 0.75, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, where any value can be alower- and upper-endpoint of a range (e.g., greater than 0.25 to 2, 0.5to 5, etc.). Here and throughout the present description, R₂O and RO caninclude one or more alkali metal oxides and alkaline earth metal oxides,respectively. Not wishing to be bound by theory, when R₂O/(R₂O+RO) isgreater than 0.25 the transmittance of the glass composition improves.

In one aspect, when the glass composition includes R₂O and RO, the molarratio of (R₂O+RO)/P₂O₅ is greater than or equal to 1. In another aspect,the molar ratio of (R₂O+RO)/P₂O₅ is greater than 1, or 2, 3, 4, 5, 6, 7,8, 9, or 10, where any value can be a lower- and upper-endpoint of arange (e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, whenthe glass composition includes R₂O and RO, the molar ratio of(R₂O+RO)/P₂O₅ is less than or equal to 1.

In one aspect, when the glass composition includes RO and not R₂O, themolar ratio of RO/P₂O₅ is greater than or equal to 1. In another aspect,the molar ratio of RO/P₂O₅ is greater than 1, or 2, 3, 4, 5, 6, 7, 8, 9,or 10, where any value can be a lower- and upper-endpoint of a range(e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, when theglass composition includes RO and not R₂O, the molar ratio of RO/P₂O₅ isless than or equal to 1.

In one aspect, when the glass composition includes R₂O and not RO, themolar ratio of R₂O/P₂O₅ is greater than or equal to 1. In anotheraspect, the molar ratio of R₂O/P₂O₅ is greater than 1, or 2, 3, 4, 5, 6,7, 8, 9, or 10, where any value can be a lower- and upper-endpoint of arange (e.g., greater than 1 to 3, 2 to 5, etc.). In other aspects, whenthe glass composition includes R₂O and not RO, the molar ratio ofR₂O/P₂O₅ is less than or equal to 1.

In one aspect, the glass compositions described herein contain TiO₂. Inone aspect, the amount of TiO₂ is from about 1 mol % to about 30 mol %.In a still further aspect, TiO₂ is present at about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,26, 27, 28, 29, or 30 mol %, where any value can be a lower- andupper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 20 mol%, etc.).

In one aspect, the glass compositions described herein contain WO₃. Inone aspect, the amount of WO₃ is from about 1 mol % to about 15 mol %.In a still further aspect, WO₃ is present at about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, or 15 mol %, where any value can be a lower-and upper-endpoint of a range (e.g., 1 mol % to 5 mol %, 5 mol % to 10mol %, 10 mol % to 15 mol %, etc.).

In one aspect, when the glass composition includes TiO₂ and/or WO₃, thesum of Nb₂O₅ with TiO₂ and/or WO₃ is in the amount of 20 mol % to 50 mol%. In a still further aspect, the sum of Nb₂O₅ with TiO₂ and/or WO₃ isat about 20, 25, 30, 35, 40, 45, or 50 mol %, where any value can be alower- and upper-endpoint of a range (e.g., 20 mol % to 30 mol %, 30 mol% to 40 mol %, etc.).

In one aspect, the glass composition includes ZnO. In this aspect, theamount of ZnO is from 0.5 mol % to about 20 mol %, or is about 0.5, 1,2, 3, 4, 5, 10, 15, or 20 mol %, where any value can be a lower- andupper-endpoint of a range (e.g., 1 mol % to 15 mol %, 5 mol % to 10 mol%, etc.). In one aspect, the sum of RO, R₂O, and ZnO is in the amount of30 mol % to 60 mol %, or is about 30, 25, 40, 45, 50, 55, or 60 mol %,where any value can be a lower- and upper-endpoint of a range (e.g., 30%to 45%, 40% to 55%, etc.).

In another aspect, the glass composition includes Al₂O₃. In this aspect,the amount of Al₂O₃ is greater than 0 mol % and less than or equal toabout 5 mol %, or is about 1, 2, 3, 4, or 5 mol %, where any value canbe a lower- and upper-endpoint of a range (e.g., 1 mol % to 5 mol %, 2mol % to 4 mol %, etc.).

In another aspect, the glass composition includes SnO₂. In this aspect,the amount of SnO₂ is greater than 0 mol % and less than or equal toabout 2 mol %, or is about 0.1, 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75,or 2.0 mol %, where any value can be a lower- and upper-endpoint of arange (e.g., 0.1 mol % to 2.0 mol %, 0.25 mol % to 1.75 mol %, etc.).

In one aspect, the glass compositions described herein further containone or more metal oxides selected from the group consisting of Rb₂O,Cs₂O, CdO, MnO₂, Y₂O₃, La₂O₃, HfO₂, Ta₂O₅, ZrO₂, Ga₂O₃, SiO₂, GeO₂,Sb₂O₃, Bi₂O₃, and combination thereof. In another aspect, the glasscompositions contain one, two, three, or four metal oxides from thoselisted above. In certain aspects, the glass compositions describedherein do not include SiO₂, Al₂O₃, MgO, TiO₂, or any combinationthereof. In another aspect, the glass compositions described herein donot include B₂O₃.

In one aspect, a first glass composition includes

(a) P₂O₅ in an amount of 15 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %;(c) an alkali metal oxide (R₂O) in an amount of 1 mol % to 35 mol %; and(d) at least two alkaline earth metal oxides (RO) in a combined amountof 5 mol % to 40 mol %,wherein the glass composition does not include ZnO and B₂O₃.

In one aspect, with respect to the first glass composition above, inanother aspect the amount of P₂O₅ is from 25 mol % to 35 mol %; theamount of Nb₂O₅ is from 20 mol % to 35 mol %; the amount of R₂O is from10 mol % to 35 mol %, and the amount of RO is from 20 mol % to 40 mol %.In a further aspect, the first glass composition includes WO₃ in theamount from about 1 mol % to about 15 mol % and/or TiO₂ in the amountfrom about 1 mol % to about 20 mol %, wherein the sum of Nb₂O₅ with TiO₂and/or WO₃ is in the amount of 20 mol % to 40 mol %.

In one aspect, with respect to the first glass composition above, R₂O isNa₂O in the amount of 1 mol % to 15 mol %, Li₂O in the amount of 1 mol %to 15 mol %, and K₂O is in the amount of 1 mol % to 10 mol %, BaO is inthe amount of 1 mol % to 25 mol %, CaO is in the amount of 1 mol % to 25mol %, and SrO is in the amount of 1 mol % to 25 mol %.

In one aspect, a second glass composition includes

(a) P₂O₅ in an amount of 15 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %;(c) at least one alkali metal oxide (R₂O) in an amount of 5 mol % to 35mol %; andwherein the glass composition does not include ZnO, B₂O₃, or an alkalineearth metal oxide (RO).

In one aspect, with respect to the second glass composition above, Nb₂O₅is in the amount of 30 mol % to 40 mol % and TiO₂ in the amount of 5 mol% to 15 mol %, P₂O₅ is in an amount of 20 mol % to 30 mol %, and R₂O isNa₂O in the amount of 5 mol % to 40 mol %, Li₂O is in the amount of 5mol % to 40 mol %, K₂O is in the amount of 5 mol % to 40 mol %, or anycombination thereof of R₂O.

In one aspect, a third glass composition includes

(a) P₂O₅ in an amount of 15 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %;(c) at least one alkaline earth metal oxide (RO) in an amount of 5 mol %to 40 mol %;wherein the glass composition does not include ZnO, B₂O₃, or an alkalimetal oxide (R₂O).

In one aspect, with respect to the third glass composition above, Nb₂O₅is in the amount of 30 mol % to 40 mol %, TiO₂ is in the amount of 5 mol% to 15 mol %, P₂O₅ is in an amount of 20 mol % to 30 mol %, BaO is inthe amount of 5 mol % to 20 mol %, CaO is in the amount of 1 mol % to 10mol %, and SrO is in the amount of 5 mol % to 20 mol %.

In one aspect, a fourth glass composition includes

(a) P₂O₅ in an amount of 20 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %;(c) an alkali metal oxide (R₂O) in an amount of 1 mol % to 35 mol %;(d) an alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol%,wherein the glass composition does not include B₂O₃.

In one aspect, with respect to the fourth glass composition above, P₂O₅is in the amount of 25 mol % to 35 mol %; Nb₂O₅ is in the amount of 20mol % to 35 mol %; ZnO is in the amount of 5 mol % to 25 mol %; R₂O isin the amount of 10 mol % to 35 mol %, and RO is in the amount of 20 mol% to 40 mol %. In a further aspect, the fourth glass compositionincludes WO₃ in the amount from about 1 mol % to about 15 mol % and/orTiO₂ in the amount from about 1 mol % to about 20 mol %, wherein the sumof Nb₂O₅ with TiO₂ and/or WO₃ is in the amount of 20 mol % to 40 mol %.

In one aspect, a fifth glass composition includes

(a) P₂O₅ in an amount of 20 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %; and(c) at least one alkali metal oxide (R₂O) in an amount of 5 mol % to 35mol %;wherein the glass composition does not include B₂O₃ or an alkaline earthmetal oxide (RO).

In one aspect, with respect to the fifth glass composition above, Nb₂O₅is in the amount of 30 mol % to 40 mol %, TiO₂ is in the amount of 5 mol% to 15 mol %, P₂O₅ is in an amount of 20 mol % to 35 mol %, ZnO is inthe amount of 1 mol % to 15 mol %, and R₂O is in the amount of 1 mol %to 35 mol %, where R₂O is Na₂O, Li₂O, K₂O, or any combination thereof.

In one aspect, a sixth glass composition includes

(a) P₂O₅ in an amount of 20 mol % to 40 mol %;(b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %; and(c) at least one alkaline earth metal oxide (RO) in an amount of 5 mol %to 40 mol %;wherein the glass composition does not include B₂O₃ or an alkali metaloxide (R₂O).

In one aspect, with respect to the sixth glass composition above, Nb₂O₅is in the amount of 30 mol % to 40 mol %, TiO₂ is in the amount of 5 mol% to 15 mol %, P₂O₅ is in an amount of 20 mol % to 35 mol %, ZnO is inthe amount of 1 mol % to 15 mol %, and RO is in the amount of 5 mol % to40 mol %, where RO is BaO, CaO, SrO, or any combination thereof.

The glass compositions described herein can be prepared using techniquesknown in the art. In one aspect, the glass compositions disclosed hereincan be prepared by melt quenching. In one aspect, P₂O₅ can be added asphosphoric acid (H₃PO₄) in combination with the additional glass-formingcomponents. Further in this aspect, when phosphoric acid is added, thebatch materials can be calcined at 350° C. to 400° C. prior to melting.In another aspect, P₂O₅ can be added as anhydrous phosphorus pentoxide.In one aspect, the batch materials are melted at 900° C. to 1,300° C. Inanother aspect, the batch materials are melted in platinum crucibles.

The glass compositions described herein have a refractive index suitablefor the use in optical articles. In one aspect, the glass compositionshave a refractive index of at least 1.75 at 587.6 nm (D-line) at 25° C.,or a refractive index at 587.6 nm at 25° C. of about 1.75, 1.80, 1.85,1.90, 1.95, or 2.00, where any value can be a lower- and upper-endpointof a range (e.g., 1.75 to 1.95, 1.90 to 2.00, etc.).

The glass compositions described herein have a density suitable for theuse in optical articles. The density is sufficiently low such that theycan be used in virtual reality or augmented reality headsets and otheroptical articles. In one aspect, the glass compositions have a densityof less than or equal to 4.0 g/cm³, or a density of 3.5 g/cm³, 3.6g/cm³, 3.7 g/cm³, 3.8 g/cm³, 3.9 g/cm³, or 4.0 g/cm³, where any valuecan be a lower- and upper-endpoint of a range (e.g., 3.5 g/cm³ to 3.9g/cm³, 3.75 g/cm³ to 4.0 g/cm³, etc.).

The glass compositions described herein have a glass thermal stabilityindex that permits the manufacture of optical articles using a number ofdifferent glass-making techniques. Not wishing to be bound by theory,the greater the glass thermal stability index the larger the windowexists for glass processing with less chance of devitrification. In oneaspect, the glass compositions have a glass thermal stability index ofgreater than or equal to 200° C., greater than or equal to 225° C., or aglass thermal stability index of 200° C., 210° C., 220° C., 230° C.,240° C., 250° C., 260° C., 270° C., 280° C., 290° C., or 300° C., whereany value can be a lower- and upper-endpoint of a range (e.g., 200° C.to 300° C., 220° C. to 270° C., etc.).

In certain aspects, the glass composition does not crystallize whenheated at the rate of 10° C./min normally utilized in thecharacterization by differential scanning calorimetry. In these aspects,there is no value for T_(x) and the glass composition does not have aglass thermal stability index as defined herein. With respect to theseglass compositions, they are desirable from the standpoint of theirforming characteristics, especially when the forming technique usedrequires a reheating step.

In one aspect, the glass compositions described herein have an Abbenumber of at least 20, or from 20 to 40. In another aspect, the Abbenumber is about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,34, 35, 36, 37, 38, 39, or 40, where any value can be a lower- andupper-endpoint of a range (e.g., 25 to 35, 30 to 40, etc.).

In one aspect, the glass compositions disclosed herein have annealingpoints of from about 450° C. to about 750° C. In another aspect, theannealing point of the glass composition is about 450, 475, 500, 525,550, 575, 600, 625, 650, 675, 700, 725, or 750, ° C., where any valuecan be a lower- and upper-endpoint of a range (e.g., 450° C. to 700° C.,500 to 650° C., 600° C. to 700° C., 650 to 750° C., etc.).

In one aspect, the glass compositions described herein have acoefficient of thermal expansion of from about 6.0 ppm/° C. to about12.0 ppm/° C. at each temperature over a range extending from roomtemperature to 300° C. In one aspect, the coefficient of thermalexpansion is about 7.5, 8, 8.5, 9, 9.5, 10, 10.5, or 11 ppm/° C., whereany value can be a lower- and upper-endpoint of a range (e.g., 8 to 10ppm/° C., 8.5 to 10.5 ppm/° C., etc.).

In one aspect, the glass compositions have a softening point of 575° C.to 850° C. as determined by ASTM C1351M. In another aspect, thesoftening point of the glass composition is about 575, 600, 625, 650,675, 700, 725, 750, 775, 800, 825, or 850° C., where any value can be alower- and upper-endpoint of a range (e.g., 600° C. to 700° C., 650 to750° C., etc.).

In one aspect, the glass compositions have an internal liquidustemperature of 875° C. to 1,200° C. In another aspect, the internalliquidus temperature of the glass composition is about 875, 900, 925,950, 975, 1,000, 1,025, 1,050, 1,075, 1,100, 1,125, 1,150, or 1,200° C.,where any value can be a lower- and upper-endpoint of a range (e.g.,900° C. to 1,100° C., 1,000 to 1,150° C., etc.).

In one aspect, the glass compositions have a Young's modulus of 50 GPato 110 GPa. In another aspect, the Young's modulus of the glasscomposition is about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105,or 110 GPa, where any value can be a lower- and upper-endpoint of arange (e.g., 60 to 80 GPa, 70 to 90 GPa, etc.).

In other aspects, the color of the glass composition can be controlled.Not wishing to be bound by theory, the oxidation of multi-valencetransition metal cations during glass production can discolor the finalglass composition. Depending on the valence states of the transitionmetals, the color of the glass compositions containing Nb, Ti, and W canvary from light yellow, dark brown to deep blue. In one aspect,discoloration of the glass composition can be achieved by heating theglass composition at or near its glass transition temperature (T_(g)) inair or an atmosphere oxygen. In one aspect, the glass composition isheated 120° C. above the glass transition temperature for 10 to 1440minutes in air or under an atmosphere of oxygen. The heat-treatment doesnot adversely affect the transmittance of the glass and as shown in theExamples, the transmittance and refractive index of the glasscomposition can be improved with the heat-treatment.

In another aspect, a component such as CeO₂ can be added during glassformation in order to reduce discoloration of the glass composition. Inone aspect, the amount of CeO₂ that can be used is from 0.001 mol % to 2mol %. As shown in the Examples, the glass transmittance and refractiveindex of the glass can be improved with the addition of CeO₂.

In one aspect, the glass compositions described herein are stable enoughthat they can be cast into large shapes approximately 1 cm thick andcooled to glass without devitrification.

In one aspect, the glass compositions disclosed herein exhibit chemicaldurability comparable to silicate compositions with similar refractiveindex. In another aspect, although typical phosphate glasses corrodeunder high moisture/high humidity conditions, the glasses disclosedherein do not deteriorate in this manner. In another aspect, the glasscompositions disclosed herein have low dispersion in addition to highrefractive index.

In one aspect, the glass compositions described herein can be used toproduce optical articles. In one aspect, the optical article istransparent. In another aspect, the glasses provided herein may bestrongly colored when formed by conventional melting in air but thecolor can be removed. In one aspect, the color is removed by annealingthe glasses in air or oxygen at temperatures near T_(g) for the glasscompositions. In another aspect, the color is removed by the addition ofan oxidation agent, e.g. CeO₂.

In another aspect, the glass compositions can be processed by varioustechniques into a powder, fiber, beads, sheets, or three-dimensionalscaffolds or shapes. Glasses with desired properties and forms can beused for their applications in optical displays, augmented realitydevices or virtual reality devices, non-linear photonic materials,sealing glasses, encapsulating glass for optical objects, separators inbatteries, optical amplification and waveguide devices.

EXAMPLES

The following examples are put forth to provide those of ordinary skillin the art with a complete disclosure and description of how thecompounds, compositions, and methods described and claimed herein aremade and evaluated, and are intended to be purely exemplary and are notintended to limit the scope of the discoveries disclosed herein. Effortshave been made to ensure accuracy with respect to numbers (e.g.,amounts, temperature, etc.) but some errors and deviations should beaccounted for. Unless indicated otherwise, parts are parts by weight,temperature is in ° C. or is at ambient temperature, and pressure is ator near atmospheric. Numerous variations and combinations of reactionconditions (e.g., component concentrations, desired solvents, solventmixtures, temperatures, pressures, and other reaction ranges andconditions) can be used to optimize the product purity and yieldobtained from the described process. Only reasonable and routineexperimentation will be required to optimize such process conditions.

Example 1: Production of Glass Compositions

The glass compositions were prepared by standard melt-quench methodologyfrom batches of metal oxide powders, metal carbonate powders and metalphosphate compound powders. P₂O₅ was added to the batch as phosphatecompounds, e.g., lithium phosphate, sodium hexametaphosphate, potassiumphosphate, calcium phosphate, barium phosphate, and/or phosphoric acid(H₃PO₄). The addition of phosphoric acid required calcining the batchesat 350-400° C. prior to melting at 900-1,300° C. in platinum cruciblesin air for 2-4 hours. Glasses, once formed, were annealed at annealingtemperature or near the glass transition temperature (T_(g)) in air forabout 2 hours then subsequently quenched to reduce internal stress. Theglass compositions were not subsequently remelted. The glasscompositions were not subsequently cleaned or subjected topost-fabrication processing. Following annealing, properties such asthermal expansion coefficient, T_(g), refractive index, density, andothers were determined.

Example 2: Sample Glass Compositions and Characterization

Several glass compositions were prepared and their properties arepresented in Tables 1-9, where the amount of each component is expressedin mol %.

The following parameters in the tables below are defined as follows:

Density. The density was measured according to ASTM C693.

Refractive Index (RI) and Abbe Number (V_(d)). RI was measured with aMetricon Model 2010 Prism Coupler instrument. RI measurements wereperformed on the Metricon Model 2010 Prism Coupler at wavelengths of 406nm, 473 nm, 532 nm, 633 nm, 790 nm and 981 nm using various lasersources. The Metricon 2010 prism coupler operates as a fully automatedrefractometer, in which the refractive index of bulk materials and/orfilms can be measured. Refractive indices of bulk materials, such as theprovided glass samples, are measured by the Metricon 2010 Prism Coupler.Measured index of refraction results were fit to a Cauchy or Sellmeierdispersion equation and constants were determined. The refractive indexfor optical glasses is specified herein at a wavelength of 587.6 nm andreferred to as R_(d) and/or nD in the tables below. When refractiveindex was measured at a different wavelength, it is noted as n519, n532,n633, and the like, where the number indicates the wavelength innanometers. Using fitted index dispersion values, the V_(D) Abbe numberwas calculated for each glass composition.

Strain point and Annealing Point. The beam bending viscosity methodmeasures the viscosity of inorganic glass from 10¹² to 10¹⁴ poise versustemperature and from this measurement, estimates of the strain point andannealing point of the glass are obtained according to ASTM C598.

Softening Point. The parallel place viscosity method measures viscosityfrom 10⁷ to 10⁹ poise versus temperature and from this measurement,estimates of a “normal softening point” of the glasses was obtained.This method is similar to ASTM C1351M.

Coefficient of Thermal Expansion (CTE). A dilatometer method was used todetermine a mean coefficient of linear thermal expansion (CTE) of theglasses according to ASTM E228.

Glass Transition Temperature (T_(g)) and Onset Temperature ofCrystallization (T_(x)). T_(g) and T_(x) were measured by differentialscanning calorimetry (DSC) with ramp rate of 10° C./min to 1000° C. inArgon atmosphere. Samples were pulverized with a mortar and pestle.About 30 mg was used for analysis. Samples were weighed using amicrobalance and placed into a Netzsch DSC 404 F1 Pegasus instrument foranalysis. The atmosphere was evacuated and backfilled in with Argon toprovide an inert atmosphere.

Liquidus Temperature. The liquidus temperature was measured by thegradient furnace method. This method conforms to the ASTM C829-81Standard Practices for Measurement of Liquidus Temperature of Glass.

Poisson's Ratio, Shear Modulus, and Young's Modulus. Young's modulus,shear modulus and Poisson's ratio were measured by Resonant UltrasoundSpectroscopy, and the instrument model is Quasar RUSpec 4000 byMagnaflux.

The following procedures were used for the Advanced Optics (AO) Test andNano Strip 2× Test to evaluate the chemical durability of each glass.The results provided in the tables below.

Advanced optics (AO) tests were performed to evaluate the chemicaldurability of the glass compositions. AO tests are typically performedin evaluating optical glasses. Each glass sample (25 mm×25 mm×1 mm,surface polished) was etched in 10 wt % HCl for 10 min at 25° C. Theratio of surface area to volume used in this test is 0.33 cm⁻¹. Afteretching for 10 minutes, the samples were quenched in deionized water andrinsed in 18 MΩ water, and then dried by high-pure nitrogen gas andplaced in a desiccator for overnight. Weight loss normalized to surfacearea (mg/cm² or mg/mm²) and weight loss percentage (wt %) werecalculated.

Nano Strip 2× Test. The dried samples were submerged in 600 ml ofNanostrip 2× solution (Capitol Scientific, 85% H₂SO₄ and <1% H₂O₂) for50 min at 70° C. with a stir at 400 rpm speed. The ratio of surface areato volume used in this test is 0.08 cm⁻¹. After 50 minutes, the sampleswere quenched in deionized water and rinsed in 18 MΩ water, and thendried by high-pure nitrogen gas and placed in a desiccator forovernight. weight loss normalized to surface area (mg/cm²) and weightloss percentage (wt %) was calculated.

TABLE 1 Component 1 2 3 4 5 6 7 8 Al₂O₃ 4.8 4.8 4.8 4.8 P₂O₅ 30.0 30.030.8 30.3 30.6 29.9 30.2 30.1 Na₂O 15.0 20.0 15.6 20.0 14.9 14.9 14.815.0 Li₂O + Na₂O + 15.0 20.0 15.6 20.0 14.9 14.9 14.8 15.0 K₂O BaO 10.05.0 10.0 5.1 10.1 10.4 9.9 10.1 ZnO 20.0 10.0 19.4 9.9 20.0 5.0 10.015.0 MgO + CaO + 30.0 15.0 29.4 15.0 30.1 15.4 19.9 25.1 BaO + SrO + ZnOR₂O + RO + 45.0 35.0 45.0 35.0 45.0 30.3 34.7 40.1 ZnO TiO₂ 10.0 10.015.0 10.4 5.2 Nb₂O₅ 25.0 25.0 24.1 24.7 19.6 19.9 19.9 19.7 Nb₂O₅ +TiO₂ + 25.0 35.0 24.1 34.7 19.6 34.9 30.3 24.9 WO₃ Properties Density(g/cm³) 3.726 3.561 3.726 3.561 3.633 3.551 3.583 3.611 nD 1.811^(a)1.844^(a) 1.811 1.844 1.761 1.832 1.807 1.788 V_(d) 30.37 22.40 27.3023.99 25.24 28.28 Strain Point (° C.) 526 559 502 568 544 520 AnnealingPoint 562 593 538 604 581 556 (° C.) Softening Point 686 714 668 729 707687 (° C.) CTE (<300° C., 7.9 7.9 8.1 8.0 7.9 8.0 on heating) in ppm/°C. T_(g onset) (° C.) 552 604 552 604 544 618 589 566 T_(x onset) (° C.)807 825 807 825 766 850 810 794 T_(x onset) − T_(g onset) 255 221 255221 222 232 221 228 (° C.) Liquidus internal 1090 1045 1035 1085 10701055 (° C.) AO weight loss 4.0 × 10⁻⁴ 1.0 × 10⁻³ 2.5 × 10⁻⁵ 3.2 × 10⁻⁵2.5 × 10⁻⁵ 3.2 × 10⁻⁵ (mg/mm²), Nanostrip 1.2 × 10⁻⁴ 4.1 × 10⁻⁵ 8.4 ×10⁻⁴ 2.5 × 10⁻⁴ 3.3 × 10⁻⁴ 1.1 × 10⁻³ (mg/mm²), Poissons Ratio 0.2560.24 0.254 0.239 0.244 0.255 Shear Modulus 33.3 35.8 32.0 36.3 34.9 33.4(GPa) Young's Modulus 83.6 88.6 80.3 89.9 87.0 83.9 (GPa) ^(a)Estimatebased on similar compositions.

TABLE 2 Component 9 10 11 12 13 14 15 16 17 18 P₂O₅ 30 30 30 30 30 25 2530.5 35.1 25.3 Li₂O 5 3 5 5 Na₂O 15 15 5 3 5 5 33.5 19.9 24.7 K₂O 5 3 55 Li₂O + Na₂O + 15 15 15 9 0 15 15 33.5 19.9 24.7 K₂O CaO 15 18 5 15 15BaO 10 15 18 15 15 15 11.3 20 24.8 SrO 30 15 ZnO 20 10 MgO + CaO + 30 3030 36 45 30 30 11.3 20 24.8 BaO + SrO + ZnO) R₂O + RO + 45 45 45 45 4545 45 44.8 39.9 49.5 ZnO TiO₂ 10.0 Nb₂O₅ 20 25 25 25 25 15 25 24.7 2525.2 WO₃ 5 5 5 Nb₂O₅ + 25 25 25 25 25 30 30 24.7 25 25.2 TiO₂ + WO₃ CeO₂0.1 0.1 0.1 0.1 0.1 Properties Density 3.819 3.717 3.633 3.674 3.813.745 3.748 3.51 3.631 3.663 (g/cm³) nD 1.788 1.793 1.807 1.816 1.8321.812 1.851 1.754 1.757 1.799 V_(d) 26.34 27.94 28.85 26.64 28.56 25.8324.18 27.84 29.13 27.06 Strain Point 533.5 547.2 (° C.) Annealing 570.2578.5 Point (° C.) Softening 667.9 716.8 739.3 739.5 742.8 666.9 691.3654.7 698.5 682 Point (° C.) T_(g onset) (° C.) 551.8 620.7 588.7 603619.4 572.9 576.9 563.5 586.4 590.8 T_(x onset) (° C.) 839.1 850.2 831832.1 827.4 812.8 809.7 861.3 793 793.7 T_(x onset) − T_(g onset) 287.3229.5 242.3 229.1 208 239.9 232.8 297.8 206.6 202.9 (° C.) Nanostrip 4.0× 10⁻⁴ 1.3 × 10⁻² 7.0 × 10⁻⁴ 2.8 × 10⁻³ 1.4 × 10⁻³ (mg/mm²) Poissons0.262 0.27 Ratio Shear 28.7 29.7 Modulus (GPa) Young's 72.6 75.4 Modulus(GPa)

TABLE 3 Component 19 20 21 22 23 24 25 26 27 28 29 30 P₂O₅ 30 25 25 2530 30 30 25 30 27.5 27.5 27.5 Li₂O 5 6 5 5 7 5 7 5 7 5 7 8 Na₂O 5 6 5 57 5 7 5 7 5 7 9 K₂O 5 5.5 5 5 6 5 6 5 6 5 6 8 Li₂O + Na₂O + 15 17.5 1515 20 15 20 15 20 15 20 25 K₂O CaO 10 12.5 12.5 12.5 8 10 8 12.5 8 119.5 7.5 BaO 10 12.5 12.5 12.5 9 10 9 12.5 9 11.5 10 7.5 SrO 10 10 10 108 0 0 10 8 10 8 7.5 ZnO 10 8 MgO + CaO + 30 35 35 35 25 30 25 35 25 32.527.5 22.5 BaO + SrO + ZnO R₂O + RO + 45 52.5 50 50 45 45 45 50 45 47.547.5 47.5 ZnO TiO₂ 5 10 15 10 10 10 10 Nb₂O₅ 25 22.5 20 15 25 25 25 1015 15 15 15 Nb₂O₅ + 25 22.5 25 25 25 25 25 25 25 25 25 25 TiO₂ + WO₃Properties Density 3.692 3.781 3.77 3.7 3.627 3.675 3.623 3.634 3.4973.648 3.564 3.473 (g/cm³) nD 1.805 1.803 1.810 1.791 1.798 1.816 1.8071.773 1.765 1.784 1.776 1.765 T_(g onset) 591 577 587 582 568 564 548581 554 587 559 543 (° C.) T_(x onset) 856 783 791 806 783 833 837 781816 795 771 762 (° C.) T_(x onset) − 265 206 204 224 215 269 289 201 261209 211 219 T_(g onset) (° C.)

TABLE 4 Component 31 32 33 34 35 36 37 38 P₂O₅ 33.2 32.1 32.6 33 31.732.3 33.1 28.2 Li₂O 10.1 Na₂O 18.3 14 21.5 18.1 13.8 21.4 21.3 8.7 K₂O5.1 Li₂O + Na₂O + K₂O 18.3 14 21.5 18.1 13.8 21.4 21.3 23.9 MgO 7 14.97.1 14.1 BaO 18.7 15.3 15.3 18.5 15.2 15 7.5 11.2 SrO 10.3 ZnO 5.6 13.75.6 MgO + CaO + BaO + 24.3 29 20.9 25.5 30.1 22.1 21.6 21.5 SrO + ZnOR₂O + RO + ZnO 42.6 43 42.4 43.6 43.9 43.5 42.9 45.4 Nb₂O₅ 24.2 24.9 2523.4 24.4 24.2 24 26.5 Nb₂O₅ + TiO₂ + WO₃ 24.2 24.9 25 23.4 24.4 24.2 2426.5 Properties Density (g/cm³) 3.691 3.705 3.631 3.661 3.649 3.6 3.4313.718 nD 1.803 1.788 1.789 1.813 1.799 1.812 1.789 1.794 V_(d) 25.2626.69 21.45 26.14 25.45 23.96 26.49 28.25 CTE (<300° C., on heating) 9.68.6 10.1 9.8 8.8 10.2 9.6 11.4 in ppm/° C. T_(g onset) (° C.) 564 575567 589 610 580 586 548 T_(x onset) (° C.) 811 819 810 824 826 839 860761 T_(x onset) − T_(g onset) (° C.) 247 244 243 235 216 259 274 213

TABLE 5 Component 39 40 41 42 43 44 45 46 P₂O₅ 25 27.5 30 25.8 26 2625.6 32.1 Li₂O 7 7 7 9.5 10.1 9.6 9.5 Na₂O 8 8 8 10 9.8 9.9 10 19.6 K₂O5 5 5 5 4.7 4.8 4.8 Li₂O + Na₂O + K₂O 20 20 20 24.5 24.6 24.3 24.3 19.6CaO 15 8.75 7.5 4.9 4.9 4.9 5 BaO 15 8.75 7.5 10.3 10.1 10.2 10.2 5 SrO9.1 9.6 4.6 4.7 ZnO 10 10 4.9 8.9 MgO + CaO + 30 27.5 25 24.3 24.6 19.724.8 13.9 BaO + SrO + ZnO R₂O + RO + ZnO 50 47.5 45 48.8 49.2 44 49.133.5 TiO₂ 5.1 10 9.9 Nb₂O₅ 20 25 25 20.2 19.8 15 15.1 24.5 WO₃ 5 5 5.110.1 Nb₂O₅ + TiO₂ + 25 25 25 25.3 24.8 30.1 25.2 34.4 WO₃ CeO₂ 0.01 0.01Properties Density (g/cm³) 3.843 3.688 3.595 3.662 3.781 3.681 3.8813.512 nD 1.801 1.822 1.808 1.798 1.787 1.800 1.765 1.861 V_(d) 26.7127.57 25.86 22.00 T_(g onset) (° C.) 547 540 539 543 522 529 489 610T_(x onset) (° C.) 772 783 826 762 764 788 827 T_(x onset) − T_(g onset)225 243 287 219 242 259 a 216 (° C.) ^(a.) No crystallization peak inDSC.

TABLE 6 Component 47 48 49 50 51 P₂O₅ 30.0 30.0 30.0 30.0 30.0 Na₂O 15.015.0 15.0 15.0 15.0 Li₂O + Na₂O + K₂O 15.0 15.0 15.0 15.0 15.0 BaO 10 1010 15 20 ZnO 20 15 10 15 10 MgO + CaO + 30 25 20 30 30 BaO + SrO + ZnOR₂O + RO + ZnO 45 40 35 45 45 Nb₂O₅ 20 25 30 20 20 WO₃ 5 5 5 5 5 Nb₂O₅ +TiO₂ + WO₃ 25 30 35 25 25 Properties Density (g/cm³) 3.818 3.853 3.8853.862 3.959 nD 1.785 1.820 1.860 1.780 1.790 T_(gonset) (° C.) 547 575606 552 580 T_(xonset) (° C.) 818 827 837 801 809 T_(xonset) −T_(gonset) (° C.) 271 252 231 250 230

TABLE 7 Mol % Component 52 53 54 55 56 57 58 59 60 61 62 63 P₂O₅ 30 3030 30 30 30 30 30 30 25 25 30 Li₂O 5 5 5 7 7 7 7 7 8.75 7 7 Na₂O 10 5 2010 7 7 7 8 8 10 8 8 K₂O 5 5 5 6 6 6 5 5 6.25 5 5 Li₂O + Na₂O + 20 15 2020 20 20 20 20 20 25 20 20 K₂O CaO 10 7.36 6.08 4.8 8 8 8 10 10 BaO 1015 5 5 8.28 6.84 5.4 9 9 9 9.99 10 SrO 5 8 10 ZnO 5 10 10 7.36 6.08 4.88 8 10 MgO + CaO + 20 25 15 15 23 19 15 25 25 25 29.99 30 BaO + SrO +ZnO R₂O + RO + 40 40 35 35 43 39 35 45 45 50 49.99 50 ZnO TiO₂ 5 10 1020 5 10 15 15 Nb₂O₅ 15 15 25 15 25 25 25 20 15 10 10 20 WO₃ 10 5 2 6 10Nb₂O₅ + 30 30 35 35 27 31 35 25 25 25 25 20 TiO₂ + WO₃ CeO₂ 0.01 0.010.001 0.001 0.01 Properties Density 3.752 3.671 3.534 3.399 3.597 3.6733.755 3.55 3.48 3.477 3.56 3.577 (g/cm³) nD 1.765 1.78 1.82 1.805 1.7951.805 1.82 1.789 1.771 1.756 1.766 1.764 T_(g onset) (° C.) 524 574 610569 542 541 547 535 526 525 548 517 T_(x onset) (° C.) 800 778 824 789806 810 786 776 803 808 T_(x onset) − 276 204 214 220 264 268 239 241277 a a 291 T_(g onset) (° C.) ^(a.) No crystallization peak in DSC.

TABLE 8 Comp. 64 65 66 67 68 69 70 71 72 73 74 75 76 77 P₂O₅ 25.7 25.625.8 25.4 25.7 30 30 30 30 30 30 30 30.0 29.3 Li₂O 10 9.9 10 10 10 7 7 77 7 7 7 6.9 6.8 Na₂O 10.3 10.4 10.3 10.4 10.6 8 8 8 8 8 8 8 7.0 7.1 K₂O5.1 5 5 5.1 4.7 5 5 5 5 5 5 5 5.9 6.0 R₂O Li₂O + 25.4 25.3 25.3 25.525.3 20 20 20 20 20 20 20 19.8 20.0 Na₂O + K₂O MgO 0.2 CaO 4.9 4.9 4.94.8 4.9 12 12 10.5 9 10 12 12 7.8 7.9 BaO 10.1 10.2 10.1 10.2 10.1 10 108.5 7 10 10 10 9.2 9.2 SrO 4.6 5 4.7 4.8 4.9 ZnO 4.5 4.5 4.5 7 6.9 5 5 811 5 5 5 8.1 8.5 MgO + 24.1 24.6 24.2 26.8 26.8 27 27 27 27 25 27 2725.3 25.6 CaO + BaO + SrO + ZnO R₂O + 49.5 49.9 49.5 52.3 52.1 47 47 4747 45 47 47 45.1 45.6 RO + ZnO La₂O₃ 1 2 Nb₂O₅ 14.6 16.9 19.7 14.8 17.120.5 18 18 18 23 22 21 24.9 25.0 WO₃ 10.1 7.6 5.1 7.5 5.1 2.5 5 5 5Nb₂O₅ + 24.7 24.5 24.8 22.3 22.2 23 23 23 23 23 22 21 24.9 25.0 TiO₂ +WO₃ SnO 2 La₂O₃ + 1 2 Ta₂O₅ + Y₂O₃ + HfO₂ Properties Density 3.855 3.8243.791 3.809 3.774 3.620 3.645 3.644 3.637 3.622 3.622 3.652 3.609 3.629(g/cm³) nD 1.767 1.777 1.793 1.760 1.771 1.773 1.761 1.760 1.764 1.7891.783 1.779 1.804 1.808 V_(d) 29.39 29.01 27.67 29.65 29.00 Annealing517 506 496 494 532 Point (° C.) T_(g onset) 489 499 511 484 495 528 517508 503 551 543 542 553 551 (° C.) T_(x onset) 747 735 719 850 777 840822 (° C.) T_(x onset) − a 248 224 a 225 322 a a a a 234 a 287 271T_(g onset) (° C.) Nanostrip 9.9 × 9.9 × 1.8 × 7.5 × (mg/mm²) 10⁻⁴ 10⁻⁴10⁻³ 10⁻⁴ ^(a.) No crystallization peak in DSC.

TABLE 9 Mol % Component 78 79 80 81 82 Al₂O₃ 0.2 0.1 0.1 P₂O₅ 30.9 31.230.8 30.6 30.6 Na₂O 33.1 32.2 19.8 20.4 19.7 Li₂O + Na₂O + K₂O 33.1 32.219.8 20.4 19.7 BaO 11.5 11.6 5.0 5.0 5.0 ZnO 9.9 9.8 9.9 MgO + CaO +11.5 11.6 15.0 14.8 14.9 BaO + SrO + ZnO R₂O + RO + ZnO 44.6 43.7 34.835.2 34.6 TiO₂ 9.9 9.9 10.0 Nb₂O₅ 24.3 24.9 24.5 24.3 24.6 Nb₂O₅ +TiO₂ + WO₃ 24.3 24.9 34.4 34.2 34.6 CeO₂ 0.1 Properties Density (g/cm³)3.515 3.509 3.426 3.385 3.563 nD 1.754 1.753 1.844 1.846 1.842T_(gonset) (° C.) 557 566 612 614 608 T_(xonset) (° C.) 846 845 845T_(xonset) − T_(gonset) (° C.) a a 234 231 237 a No crystallization peakin DSC.

TABLE 10 Mol % Component 83 84 85 86 87 88 89 90 91 92 B₂O₃ 2.5 5.0 2.82.8 2.8 2.5 2.5 5.0 P₂O₅ 30.0 27.5 25.0 25.3 25.1 25.0 30.0 30.0 30.030.0 Li₂O 7.0 7.0 7.0 10.0 8.9 9.8 10.2 7.9 8.4 7.3 Na₂O 8.0 8.0 8.0 9.79.4 9.7 10.2 7.9 8.4 7.3 K₂O 5.0 5.0 5.0 4.2 3.8 4.2 4.5 3.5 3.8 3.3Li₂O + Na₂O + K₂O 20.0 20.0 20.0 23.9 22.1 23.7 25.0 19.3 20.6 17.9 CaO12.0 12.0 12.0 4.9 4.9 4.9 2.8 4.4 4.7 4.1 BaO 10.0 10.0 10.0 9.1 9.49.2 5.0 7.9 8.4 7.3 SrO 4.9 3.8 5.1 2.2 3.5 3.8 3.3 ZnO 5.0 5.0 5.0 7.04.6 4.6 5.0 5.0 5.0 5.0 MgO + CaO + BaO + 27.0 27.0 27.0 25.9 22.7 23.815.0 20.8 21.9 19.6 SrO + ZnO R₂O + RO + ZnO 47.0 47.0 47.0 49.8 44.847.5 40.0 40.0 42.5 37.5 Nb₂O₅ 23.0 23.0 23.0 14.6 17.2 17.0 17.5 17.517.5 17.5 WO₃ 7.6 9.9 7.5 10.0 10.0 10.0 10.0 Nb₂O₅ + TiO₂ + WO₃ 23.023.0 23.0 22.2 27.1 24.5 27.5 27.5 27.5 27.5 Properties Density (g/cm³)3.590 3.608 3.642 3.788 3.875 3.801 3.658 3.758 3.783 3.729 nD 1.7871.797 1.807 1.761 1.796 1.782 1.760 1.770 1.772 1.772 V_(d) 30.31 27.2628.73 Strain Point (° C.) 464 Annealing Point (° C.) 498 Softening point(° C.) 613 T_(g onset) (C) 542 529 524 483 503 497 492 514 512 518T_(x onset) (C) 807 790 767 815 786 T_(x onset) − T_(g onset) 265 262243 a a a a 302 a 268 (° C.) ^(a.) No crystallization peak in DSC.

TABLE 11 Mol % Component 93 94 95 96 97 98 99 100 101 102 B₂O₃ 7.5 2.52.5 2.8 2.9 2.8 P₂O₅ 30.0 30.0 30.0 25.0 25.0 24.7 24.6 25.1 24.9 25.1Li₂O 6.8 8.4 7.3 10.0 10.0 9.5 9.7 8.3 8.8 8.5 Na₂O 6.8 8.4 7.3 10.010.0 9.9 9.5 8.7 8.9 8.7 K₂O 3.0 3.8 3.3 5.0 5.0 4.9 4.8 3.8 4.0 3.7Li₂O + Na₂O + K₂O 16.5 20.6 17.9 25.0 25.0 24.3 24.0 20.7 21.7 21.0 CaO3.8 4.7 4.1 5.0 5.0 5.1 5.1 5.1 5.0 5.1 BaO 6.8 8.4 7.3 10.0 10.0 9.910.1 9.0 9.0 9.1 SrO 3.0 3.8 3.3 5.0 5.0 4.9 5.0 4.0 3.9 3.9 ZnO 5.0 5.05.0 5.0 5.0 5.4 5.4 5.0 5.0 5.1 MgO + CaO + BaO + 18.5 21.9 19.6 25.025.0 25.3 25.6 23.1 22.9 23.2 SrO + ZnO R₂O + RO + ZnO 35.0 42.5 37.550.0 50.0 49.6 49.6 43.8 44.6 44.1 TiO₂ 4.7 5.5 Nb₂O₅ 17.5 17.5 17.511.9 6.9 15.4 15.4 18.0 17.4 17.6 WO₃ 10.0 7.5 12.5 8.5 12.6 10.3 10.310.2 10.0 10.1 Nb₂O₅ + TiO₂ + WO₃ 27.5 25.0 30.0 25.0 25.0 25.7 25.728.2 27.4 27.8 CeO₂ 0.02 0.2 0.02 0.2 0.2 Properties Density (g/cm³)3.702 3.677 3.814 3.809 3.895 3.878 3.896 3.860 3.865 3.656 nD 1.7701.760 1.785 1.775 1.755 1.772 1.775 1.795 1.792 1.760 V_(d) Strain Point(° C.) 462 479 Annealing Point (° C.) 497 513 T_(g onset) (° C.) 519 507521 500 472 493 493 504 505 506 T_(x onset) (° C.) 767 782 729T_(x onset) − T_(g onset) (° C.) 249 a 262 228 a a a a a a a. Nocrystallization peak in DSC.

TABLE 12 Mol % Component 103 104 105 106 107 108 109 110 111 112 B₂O₃2.8 2.8 2.8 2.8 P₂O₅ 30.1 25.2 25.1 25.1 30.3 30.4 30.2 25.4 25.5 25.4Li₂O 8.4 9.8 9.9 10.0 6.9 6.8 6.9 9.1 9.1 9.0 Na₂O 8.5 10.2 10.2 10.27.6 7.5 7.6 9.0 9.0 9.0 K₂O 3.7 4.8 4.9 4.9 5.9 5.9 5.9 3.9 3.9 3.9Li₂O + Na₂O + K₂O 20.6 24.8 25.0 25.1 20.4 20.2 20.4 22.0 22.0 22.0 CaO4.8 5.1 5.1 5.0 7.7 7.7 7.7 4.8 4.8 4.8 BaO 8.4 10.1 10.1 10.1 9.1 9.19.0 9.1 9.1 9.1 SrO 3.5 4.9 4.9 4.9 3.8 3.9 3.9 ZnO 5.0 4.6 4.6 4.6 7.37.3 7.2 5.1 4.9 4.9 MgO + CaO + BaO + 21.6 24.7 24.7 24.6 24.1 24.1 23.922.9 22.8 22.7 SrO + ZnO R₂O + RO + ZnO 42.2 49.5 49.7 49.7 44.5 44.344.3 44.9 44.8 44.7 Nb₂O₅ 17.4 14.6 14.6 14.5 24.3 24.5 24.7 17.3 17.317.4 WO₃ 7.5 10.3 10.2 10.2 9.6 9.6 9.7 Nb₂O₅ + TiO₂ + WO₃ 24.9 24.924.8 24.7 24.3 24.5 24.7 27.0 26.9 27.1 CeO₂ 0.02 Ta₂O₅ 0.4 0.4 0.4 0.70.7 0.7 Properties Density (g/cm³) 3.675 3.842 3.816 3.863 3.594 3.5903.597 nD 1.760 1.768 1.804 1.790 1.790 1.794 Strain Point (° C.) 446 501Annealing Point (° C.) 478 537 Softening point (° C.) 591 671 CTE (<300°C., on heating) 12.2 9.2 10.8 ppm/(° C.) T_(g onset) (° C.) 505T_(x onset) (° C.) T_(x onset) − T_(g onset) (° C.) a Liquidus Internal(° C.) 900 1015 a. No crystallization peak in DSC.

TABLE 13 Mol % Component 113 114 115 116 B₂O₃ 2.6 P₂O₅ 25.7 30.2 31.2 30Li₂O 16.5 Na₂O 16.5 20.9 13.9 24.7 K₂O 7.0 R₂O (Li₂O + Na₂O + K₂O) 40.020.9 13.9 24.7 CaO BaO 4.7 9.6 SrO ZnO 3.5 9.6 19.5 RO 4.7 9.6 RO +ZnO(MgO + CaO + 3.5 14.3 29.1 BaO + SrO + ZnO) R₂O + RO + ZnO 43.5 35.243.0 24.7 TiO₂ 9.6 10 Nb₂O₅ 17.6 24.1 25.1 35.3 WO₃ 10.0 Nb₂O₅ + TiO₂ +WO₃ 27.6 33.7 25.1 45.3 CeO₂ 0.8 0.8 Ta₂O₅ 0.6 Properties Density(g/ccm³) 3.509 3.523 nD 1.755 1.848 1.818 1.904 V_(d) 21.88 25.30 20.86Strain Point 558 531 622.9 Annealing Point 594 566 655.8 Softening point720 763 T_(gonset) (° C.) 454 669 T_(xonset) (° C.) (ExPC 1 onset ° C.)841 T_(xonset) − T_(gonset) a 172 a No crystallization peak in DSC.

Example 3: Glass Compositions with Refractive Index Greater Than 1.8

Glass compositions as disclosed herein having refractive index higherthan 1.8 are presented in Tables 14 through 21 along with selectedproperties. Abbreviations representing properties not already listed inExample 2 are reviewed below:

TABLE 14 Component 117 118 119 120 121 Li₂O 5 5 5 5 5 Na₂O 5 5 5 5 5 K₂O5 5 5 5 5 CaO 12.5 11.25 10 9 7 BaO 12.5 11.25 10 9 7 ZnO 10 10 10 9.58.5 TiO₂ 2.5 Nb₂O₅ 25 27.5 30 30 30 WO₃ 7.5 P₂O₅ 25 25 25 25 25Properties Density 3.86 3.85 3.835 3.977 (g/cm³) n532 1.869 1.879 1.8921.906 1.921 nD 1.859 1.868 1.881 1.894 1.908 n633 1.850 1.86 1.872 1.8851.899

TABLE 15 Component 122 123 124 125 126 127 128 129 130 Li₂O 5 5 5 5 5 55 5 5 Na₂O 5 5 5 5 5 5 5 5 5 K₂O 5 5 5 5 5 5 5 5 5 CaO 9 9 9 9 9 9 8 812.5 BaO 9.5 9.5 9.5 9.5 9.5 9.5 9 9 12.5 ZnO 9 9 9 9 9 9 8 8 TiO₂ 5 7.10 7.5 7.5 Nb₂O₅ 27.5 25 22.5 27.5 25 22.5 25 25 25 WO₃ 5 7.5 10 7.5P₂O₅ 25 25 25 25 25 25 27.5 27.5 27.5 Properties Density (g/cm³) 3.8253.794 3.76 3.946 3.979 3.993 3.719 3.902 3.721 n532 1.903 1.894 1.8861.896 1.884 1.871 1.879 1.867 1.871 nD 1.89 1.882 1.874 1.884 1.872 1.861.868 1.856 1.859 n633 1.881 1.873 1.864 1.875 1.863 1.851 1.859 1.8471.851 T_(g) 590 586 582 578 567 559 587 570 609 T_(x) 720 728 741 707720 743 797 815 806 T_(x) − T_(g) 130 142 159 129 153 184 210 245 197CTE(α)(10⁷/° C.) 83.5 Nanostrip (mg/cm²) 0.004 0.015 0.006 0.012

TABLE 16 Component 131 132 133 134 135 136 137 138 Li₂O 5 5 5 5 5 5 5 5Na₂O 5 5 5 5 5 5 5 5 K₂O 5 5 5 5 5 5 5 5 CaO 9 9 9 10 8 7.5 8 7.5 BaO9.5 9.5 9.5 11 8 7.5 8 7.5 ZnO 9 9 9 11 9 7.5 9 7.5 TiO₂ 2.5 2.5 10 12.512.5 15 Nb₂O₅ 32.5 30 30.5 25 25 25 22.5 22.5 WO₃ 2 2.5 P₂O₅ 25 25 25 2325 25 25 25 Properties Density (g/cm²) 3.881 3.851 3.908 3.946 3.7673.748 3.736 3.711 n519 1.922 1.914 1.913 1.892 1.911 1.922 1.902 1.913nD 1.906 1.898 1.897 1.877 1.895 1.906 1.886 1.897 n633 1.896 1.8891.888 1.868 1.885 1.895 1.876 1.887 T_(g) 596 586 581 589 577 584 T_(x)700 703 717 724 726 735 T_(x) − T_(g) 104 117 136 135 149 151 a (10⁻⁷/°C.) 80.3 83.2 78.4 80 83 Nanostrip (mg/cm²) 0.004 0.023 0.03 0.028 0.006

TABLE 17 Component 139 140 141 142 143 144 145 146 Li₂O 5 5 5 5 5 5 5 5Na₂O 5 5 5 5 5 5 5 5 K₂O 5 5 5 5 5 5 5 5 MgO 5.5 4 4 CaO 8 7.5 5 4 4 6.56 5 BaO 8 7.5 8 8 8 6.5 5.5 5 ZnO 9 7.5 9 9 9 7 6 6 TiO₂ 5 10 12.5 20 2529 Nb₂O₅ 25 25 27.5 25 22.5 20 17.5 15 WO₅ 10 12.5 P₂O₅ 25 25 25 25 2525 25 25 Properties Density (g/cm³) 4.018 4.06 3.777 3.742 3.646 3.5833.536 n519 1.895 1.904 1.912 1.903 n532 1.909 1.913 1.912 nD 1.88 1.8881.897 1.888 1.896 1.899 1.899 n633 1.871 1.879 1.887 1.878 1.887 1.8891.889 T_(g) 579 574 585 590 593 T_(x) 689 699 772 781 815 T_(x) − T_(g)110 125 187 191 221 a (10⁻⁷/° C.) 81.4 81.2 83.8 80.3 Nanostrip (mg/cm²)0.012 0.037

TABLE 18 Component 147 148 149 150 151 152 153 154 Li₂O 5 5 5 5 5 5 5 5Na₂O 5 5 5 5 5 5 5 5 K₂O 5 5 5 5 5 5 5 5 CaO 4.14 8 7.5 7 6.5 6 5.5 7.5BaO 4 7.5 7 7 6 6 5.5 7 ZnO 5 9 7.5 7.5 7 7 6 7.5 TiO₂ 11.25 10 15 15 2020 20 10 SnO₂ 0.5 0.5 1 0.5 1 Nb₂O₅ 35.75 25 22.5 22.5 20 20 21 26 Al₂O₃2 2 P₂O₅ 24.86 25 25 25 25 25 25 25 Properties Density (g/cm³) 3.7853.769 3.714 3.722 3.654 3.663 3.614 3.731 n519 1.915 1.911 n532 1.9861.907 1.909 1.909 1.912 1.913 nD 1.971 1.893 1.896 1.896 1.898 1.8991.899 1.895 n633 1.959 1.885 1.887 1.887 1.889 1.89 1.888 1.885 T_(g)585 582 T_(x) 699 693 T_(x) − T_(g) 114 111 Nanostrip (mg/cm²) 0.0070.004

TABLE 19 Component 155 156 157 158 159 160 161 162 163 Li₂O 7 5 5 5 5 55 Na₂O 8 8 15 5 5 5 5 5 5 K₂O 7 5 5 5 5 5 5 CaO 8 8 8 24 11 11 SrO 13 1813 BaO 8 8 8 24 29 11 ZnO 8 8 8 TiO₂ 10 10 10 10 10 10 10 Nb₂O₅ 26 26 2626 26 31 26 31 26 P₂O₅ 25 25 25 25 25 25 25 25 25 Properties Density(g/cm³) 3.797 3.746 3.779 3.557 3.979 4.097 3.687 3.792 3.874 n519 1.9281.901 1.91 1.91 1.899 1.889 1.906 1.894 1.899 nD 1.911 1.885 1.894 1.8941.884 1.875 1.89 1.879 1.884 n633 1.901 1.876 1.884 1.884 1.874 1.8661.88 1.87 1.874 T_(g) 620 628 614 617 T_(x) 723 811 747 804 T_(x) −T_(g) 103 183 133 187 Nanostrip (mg/cm²) <0.001 0.014 0.044

TABLE 20 Component 164 165 166 167 168 169 170 171 172 Li₂O 6.6 6.6 6.65 5 5 3.3 3.3 3.3 Na₂O 6.8 6.8 6.8 5 5 5 3.4 3.4 3.4 K₂O 6.6 6.6 6.6 5 55 3.3 3.3 3.3 CaO 5 7 8 7 8 10 8 10 12 SrO 4.5 6 8 6 8 9.5 8 9.5 11 BaO4.5 6 8 6 8 9.5 8 9.5 11 TiO₂ 20 10 20 10 20 10 Nb₂O₅ 21 26 31 21 26 3121 26 31 P₂O₅ 25 25 25 25 25 25 25 25 25 Properties Density 3.585 3.6943.795 3.663 3.781 3.876 3.759 3.857 3.948 (g/cm³) n532 1.903 1.893 1.8821.912 1.901 1.89 1.922 1.909 1.898 nD 1.89 1.881 1.871 1.899 1.889 1.8791.909 1.897 1.887 n633 1.88 1.872 1.862 1.89 1.88 1.87 1.899 1.888 1.878T_(g) 607 604 602 625 623 622 638 637 633 T_(x) 769 758 730 787 787 751815 811 770 T_(x)-T_(g) 162 155 127 162 165 130 177 175 137

TABLE 21 Component 173 174 175 176 177 Li₂O 5 5 5 5 5 Na₂O 5 5 5 5 5 K₂O5 5 5 5 5 CaO 5 5 7 5 8 SrO 3 5 BaO 4 5 6 5 7 ZnO 4 TiO₂ 15 15 15 10 10Nb₂O₅ 32 32 32 35 35 P₂O₅ 25 25 25 25 25 Properties Density (g/cm³)3.747 3.766 3.759 3.823 3.825 n532 1.99 1.981 1.981 1.98 1.985 nD 1.9741.966 1.966 1.965 1.97 n633 1.962 1.954 1.954 1.954 1.958 Nanostrip(mg/cm²) 0.012 0.014 0.013 0.006

Glass compositions as disclosed herein having refractive index higherthan 1.8 are presented in Tables 22 through 25 along with selectedproperties. Abbreviations representing properties not already listedpreviously herein are reviewed below:

TABLE 22 Composition 178 179 180 181 182 183 184 188 188 187 188 Mol %Batched P₂O₅ 30 30 30 27.5 25 25 25 30 30 30 30 Na₂O 25 15 25 15 5 5 BaO10 5 10 12.5 17.5 10 12.5 12.5 SrO 32.5 5 10 12.5 17.5 10 12.5 12.5 ZnO5 5 5 10 TiO₂ 10 25 10 15 10 10 10 10 10 Nb₂O₅ 35 20 30 20 35 35 35 3530 30 30 WO₃ 5 5 5 5 5 Compositional Reduced P₂O5 30 30 30 28 25 25 2530 30 30 30 R₂O 25 15 25 0 15 5 0 0 5 0 0 RO 0 10 0 33 10 20 25 35 20 2525 ZnO 0 0 0 0 5 5 5 0 0 0 10 TiO₂ 10 25 10 15 10 10 10 0 10 10 0 Nb₂O₅35 20 30 20 35 35 35 35 30 30 30 WO₃ 0 0 5 5 0 0 0 0 5 5 5 (R₂O + RO)/0.83 0.83 0.83 1.18 1.00 1.00 1.00 1.17 0.83 0.83 0.83 P₂O₅ R₂O + RO +25 25 25 33 30 30 30 35 25 25 35 ZnO R₂O/ 1 1 1 0 1 0 0 0 0 0 0 (R₂O +RO) Properties Density 3.523 3.564 3.587 3.949 3.823 3.983 4.093 4.0543.922 4.006 4.075 (g/cm³) nD 1.9039 1.9292 1.8600 1.8808 1.9572 1.97391.9783 1.8992 1.9228 1.9293 1.8921 V_(d) 20.86 22.17 18.88 19.56 19.4122.20 19.94 20.25 22.38 CTE 7.6 7.8 7.2 6.6 6.1 6.9 6.0 6.0 5.9 (<300°C., on heating) (ppm/° C.) Annealing 656 655 633 652 676 712 683 715 663Point (13) (° C.) Strain Point 623 621 600 618 643 678 649 680 628(14.5) (° C.) Softening Point 763 766 754 827 806 818 786 (7.6) (° C.)T_(g onset) (° C.) 669 670 655 700 644 665 690 723 698 724 675T_(x onset) (° C.) 841 829 854 855 748 775 792 888 857 877 842T_(x onset) - T_(g) 172 159 200 155 104 110 103 165 159 154 167 (° C.)Liquidus 1155 Internal (° C.) AO weight loss 2.00E−04 4.16E−05 (mg/mm²)Nanostrip <2E−06 8.32E−05 (mg/mm²) Poisson's Ratio 0.242 0.242 0.2490.251 0.255 0.247 0.241 0.247 0.258 Shear Modulus 38.2 38.4 40.4 40.840.0 36.2 37.5 38.7 36.7 (GPa) Young's 94.9 95.4 100.9 102.0 100.3 90.593.1 96.4 92.2 Modulus (GPa)

TABLE 23 Composition 189 190 191 192 193 194 195 196 197 198 Mol %Batched P₂O₅ 25 20 30 30 30 25 30 30 30 30 Li₂O 5 5 Na₂O 5 5 20 15 20 2525 25 25 K₂O 5 5 5 5 CaO 15 15 1 BaO 15 15 5 10 25 SrO 5 ZnO 10 10 TiO₂10 10 10 5 22 10 10 10 10 Nb₂O₅ 20 25 25 30 35 22 35 35 35 35 WO₃ 5 CeO₂0.1 0.1 0.01 0.001 0.01 0.1 Compositional Reduced P₂O₅ 25 20 30 30 30 2530 30 30 30 R₂O 15 15 20 15 25 5 25 25 25 25 RO 30 30 5 10 5 26 0 0 0 0ZnO 0 0 10 10 0 0 0 0 0 0 TiO₂ 10 10 10 0 5 22 10 10 10 10 Nb₂O₅ 20 2525 30 35 22 35 35 35 35 WO₃ 0 0 0 5 0 0 0 0 0 0 (R₂O + RO)/P₂O₅ 1.802.25 0.83 0.83 1.00 1.24 0.83 0.83 0.83 0.83 R₂O + RO + ZnO 45 45 35 35R₂O/(R₂O + RO) 0 0 1 1 Properties Density (g/cm³) 3.803 3.879 3.5123.885 3.54 3.957 3.515 3.523 3.483 3.522 nD 1.8797 1.8995 1.8612 1.86001.8664 1.9096 1.9051 1.9034 1.9037 1.9038 V_(d) 23.77 22.75 22.00 21.2021.19 Softening Point (° C.) 720 T_(g onset) (° C.) 621 600 610 606 676T_(x onset) (° C.) 803 710 827 837 851 T_(x onset) - T_(g onset) (° C.)181 110 216 231 176

TABLE 24 Composition 199 200 201 202 203 204 205 206 207 208 Mol %Batched P₂O₅ 30 30 30 30 25 30 30 30 25 30 Na₂O 15 15 15 15 25 25 15 2525 K₂O 25 BaO 10 10 10 10 SrO 10 TiO₂ 25 25 25 25 10 10 10 10 10 10Nb₂O₅ 20 20 20 20 35 35 35 35 35 35 WO₃ 5 5 CeO₂ 0.001 0.01 0.1Compositional Reduced P₂O₅ 30 30 30 30 25 30 30 30 25 30 R₂O 15 15 15 1525 25 25 15 25 25 RO 10 10 10 10 0 0 0 10 0 0 TiO₂ 25 25 25 25 10 10 1010 10 10 Nb₂O₅ 20 20 20 20 35 35 35 35 35 35 WO₃ 0 0 0 0 5 0 0 0 5 0(R₂O +RO)/P₂O₅ 0.83 0.83 0.83 0.83 1.00 0.83 0.83 0.83 1.00 0.83 R₂O +RO 25 25 25 25 25 25 25 25 25 25 R₂O/(R₂O + RO) 0.60 0.60 0.60 0.60 1 11 0.60 1 1 Properties Density (g/cm³) 3.55 3.55 3.549 3.55 3.726 3.5333.442 3.678 3.748 nD 1.8828 1.8828 1.8823 1.8824 1.9476 1.9021 1.86141.9252 1.9470 1.9178 T_(g onset) (° C.) 653 675 714 686 654 T_(x onset)(° C.) 770 860 852 866 772 T_(x onset) - T_(g onset) (° C.) 117 184 138181 117

TABLE 25 Composition 209 210 211 212 213 214 215 216 217 218 Mol %Batched P₂O₅ 30 30 30 25 30 30 30 25 25 25 Na₂O 15 10 10 7.64 18.25 2020 20 K₂O 5 5 25 17.36 6.75 CaO 5 BaO 10 10 5 12.5 20 20 20 SrO 5 12.5TiO₂ 25 25 25 10 10 10 10 Nb₂O₅ 20 20 20 35 35 35 35 35 35 35Compositional Reduced P₂O₅ 30 30 30 25 30 30 30 25 25 25 R₂O 15 15 15 025 25 25 20 20 20 RO 10 10 10 30 0 0 0 20 20 20 TiO₂ 25 25 25 10 10 1010 0 0 0 Nb₂O₅ 20 20 20 35 35 35 35 35 35 35 (R₂O + RO)/P₂O₅ 0.83 0.830.83 1.20 0.83 0.83 0.83 1.60 1.60 1.60 R₂O + RO 25 25 25 30 25 25 25 4040 40 R20/(R20+30RO) 0.60 0.60 0.60 0 1 1 1 0.50 0.50 0.50 PropertiesDensity (g/cm³) 3.611 3.535 4.046 nD 1.8896 1.9172 1.9099 1.9846 1.86001.8800 1.9000 1.8886 1.8888 1.8896

Example 4: Controlling the Color of the Glass

A couple of different approaches were examined to control the color ofthe glass compositions.

In one experiment, glass composition 116 (Table 13) was heated at 660°C. with oxygen purge for 0.5 hour and 1 hour (FIG. 1A) and in air at640° C. for 1 hour (FIG. 1B). Heat-treatment under both conditionsbleached the color of the glass and improved the transmittance in therange of 350-500 μm as shown in FIGS. 1A and 1B.

In another experiment, glass composition 4 (Table 1) was heated at 660°C. with oxygen purge for 16 hours. As shown in FIG. 2, the glasscomposition that was heated under oxygen increased the refractive indexof the glass compared to the same glass that was not heated underoxygen.

In another experiment, the addition of CeO₂ was added to several glasscompositions produced herein in order to modify the color of the glass(Table 26). Glass composition 4 did not include CeO₂ and was used as thecontrol. Glass compositions 118-120 contained from 0.01-1 mol % mol %CeO₂. The glass compositions prepared with CeO₂ in general had a higherrefractive index (FIG. 3A) and percent transmittance (FIG. 3B) comparedto glass composition 4.

TABLE 26 Base glass Base glass with CeO₂ addition (without CeO₂)(0.001-1 mol %) 4 117 (0.001% CeO₂), 118 (0.01% CeO₂), 119 (0.1% CeO₂),120 (0.8% CeO₂) 3 121 (0.8% CeO₂) 45 122 (0.02% CeO₂), 123 (0.2% CeO₂)87 124 (0.02% CeO₂), 125 (0.2% CeO₂) 94 126 (0.2% CeO₂), 127 (0.02%CeO₂)

Clause 1 of the present disclosure extends to:

A glass composition comprising:

-   -   (a) P₂O₅ in an amount of 15 mol % to 40 mol %;    -   (b) Nb₂O₅ is in an amount of 10 mol % to 50 mol %; and one of        the following:        -   (i) an alkali metal oxide (R₂O) in an amount of 1 mol % to            35 mol %; at least two alkaline earth metal oxides (RO) in a            combined amount of 5 mol % to 40 mol %, and            -   wherein the glass composition does not include ZnO and                B₂O₃;        -   (ii) at least one alkali metal oxide (R₂O) in an amount of 5            mol % to 35 mol %; and            -   wherein the glass composition does not include ZnO,                B₂O₃, or an alkaline earth metal oxide (RO); or        -   (iii) at least one alkaline earth metal oxide (RO) in an            amount of 5 mol % to 40 mol %; and            -   wherein the glass composition does not include ZnO,                B₂O₃, or an alkali metal oxide (R₂O).

Clause 2 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises

-   -   an alkali metal oxide (R₂O) in an amount of 5 mol % to 35 mol %;    -   at least two alkaline earth metal oxides (RO) in a combined        amount of 5 mol % to 40 mol %, and    -   wherein the glass composition does not include ZnO and B₂O₃.

Clause 3 of the present disclosure extends to:

The glass composition of clauses 1 or 2, wherein the molar ratio of(R₂O+RO)/P₂O₅ is greater than or equal to 1.

Clause 4 of the present disclosure extends to:

The glass composition of clauses 1 or 2, wherein the molar ratio of(R₂O+RO)/P₂O₅ is less than or equal to 1.

Clause 5 of the present disclosure extends to:

The glass composition of clauses 1 or 2, wherein the molar ratio ofR₂O/(R₂O+RO) is greater than 0.25.

Clause 6 of the present disclosure extends to:

The glass composition of any of clauses 1-5, wherein P₂O₅ is in theamount of 15 mol % to 30 mol %.

Clause 7 of the present disclosure extends to:

The glass composition of any of clauses 1-6, wherein Nb₂O₅ is in theamount of 15 mol % to 30 mol %.

Clause 8 of the present disclosure extends to:

The glass composition of any of clauses 1-7, wherein P₂O₅ is in theamount of 20 mol % to 30 mol %.

Clause 9 of the present disclosure extends to:

The glass composition of any of clauses 1-8, wherein Nb₂O₅ is in theamount of 20 mol % to 30 mol %.

Clause 10 of the present disclosure extends to:

The glass composition of any of clauses 1-9, wherein R₂O is Na₂O, Li₂O,K₂O, or any combination thereof.

Clause 11 of the present disclosure extends to:

The glass composition of any of clauses 1-10, wherein R₂O comprises Na₂Oin the amount of 1 mol % to 35 mol %.

Clause 12 of the present disclosure extends to:

The glass composition of any of clauses 1-11, wherein R₂O comprises Li₂Oin the amount of 1 mol % to 15 mol %.

Clause 13 of the present disclosure extends to:

The glass composition of any of clauses 1-12, wherein R₂O comprises K₂Oin the amount of 1 mol % to 10 mol %.

Clause 14 of the present disclosure extends to:

The glass composition of any of clauses 1-13, wherein R₂O comprises Na₂Oin the amount of 1 mol % to 15 mol %, Li₂O in the amount of 1 mol % to15 mol %, K₂O in the amount of 1 mol % to 10 mol %, or any combinationthereof.

Clause 15 of the present disclosure extends to:

The glass composition of any of clauses 1-14, wherein RO comprises BaOin the amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to25 mol %.

Clause 16 of the present disclosure extends to:

The glass composition of any of clauses 1-15, wherein RO comprises BaOin the amount of 1 mol % to 25 mol % and MgO in the amount of 1 mol % to25 mol %.

Clause 17 of the present disclosure extends to:

The glass composition of any of clauses 1-16, wherein RO comprises BaOin the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 25mol %, SrO in the amount of 1 mol % to 25 mol %, or any combinationthereof.

Clause 18 of the present disclosure extends to:

The glass composition of any of clauses 1-17, wherein R₂O comprises Na₂Oin the amount of 1 mol % to 15 mol %, Li₂O in the amount of 1 mol % to15 mol %, and K₂O in the amount of 1 mol % to 10 mol %, and RO comprisesBaO in the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol %to 25 mol %, and SrO in the amount of 1 mol % to 25 mol %.

Clause 19 of the present disclosure extends to:

The glass composition of any of clauses 1-18, wherein the compositionfurther comprises TiO₂ and/or WO₃, wherein the amount of Nb₂O₅ an amountof TiO₂ and/or an amount of WO₃, or any combination thereof, sums to 20mol % to 50 mol %.

Clause 20 of the present disclosure extends to:

The glass composition of any of clauses 1-19, wherein the compositionfurther comprises TiO₂ in an amount of 1 mol % to 30 mol %.

Clause 21 of the present disclosure extends to:

The glass composition of any of clauses 1-20, wherein the compositionfurther comprises WO₃ in an amount of 1 mol % to 15 mol %.

Clause 22 of the present disclosure extends to:

The glass composition of any of clauses 1-21, wherein the compositionfurther comprises Al₂O₃ in an amount of 1 mol % to 5 mol %.

Clause 23 of the present disclosure extends to:

The glass composition of any of clauses 1-22, wherein the compositionfurther comprises CeO₂ in an amount of 0.001 mol % to 1.0 mol %.

Clause 24 of the present disclosure extends to:

The glass composition of any of clauses 1-23, wherein the glasscomposition does not include SiO₂, Al₂O₃, MgO, TiO₂, or any combinationthereof.

Clause 25 of the present disclosure extends to:

The glass composition of any of clauses 1-24, wherein the glasscomposition comprises Nb₂O₅ in the amount of 15 mol % to 25 mol % andTiO₂ in the amount of 15 mol % to 25 mol %.

Clause 26 of the present disclosure extends to:

The glass composition of any of clauses 1-25, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 27 of the present disclosure extends to:

The glass composition of any of clauses 1-26, wherein the glasscomposition comprises Nb₂O₅ in the amount of 15 mol % to 25 mol %, TiO₂in the amount of 15 mol % to 25 mol %, and P₂O₅ in an amount of 20 mol %to 30 mol %.

Clause 28 of the present disclosure extends to:

The glass composition of any of clauses 1-27, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 29 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises

-   -   at least one alkali metal oxide (R₂O) in an amount of 5 mol % to        35 mol %; and wherein the glass composition does not include        ZnO, B₂O₃, or an alkaline earth metal oxide (RO).

Clause 30 of the present disclosure extends to:

The glass composition of clause 29, wherein the molar ratio of R₂O/P₂O₅is greater than or equal to 1.

Clause 31 of the present disclosure extends to:

The glass composition of clause 29, wherein the molar ratio of R₂O/P₂O₅is less than or equal to 1.

Clause 32 of the present disclosure extends to:

The glass composition of any of clauses 29-31, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol % andTiO₂ in the amount of 5 mol % to 15 mol %.

Clause 33 of the present disclosure extends to:

The glass composition of any of clauses 29-32, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 34 of the present disclosure extends to:

The glass composition of any of clauses 29-33, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol % andTiO₂ in the amount of 5 mol % to 15 mol %, and P₂O₅ in an amount of 20mol % to 30 mol %.

Clause 35 of the present disclosure extends to:

The glass composition of any of clauses 29-34, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 36 of the present disclosure extends to:

The glass composition of any of clauses 29-35, wherein R₂O is Na₂O,Li₂O, K₂O, or any combination thereof.

Clause 37 of the present disclosure extends to:

The glass composition of any of clauses 29-36, wherein R₂O comprisesNa₂O in the amount of 5 mol % to 40 mol %, Li₂O in the amount of 5 mol %to 40 mol %, K₂O in the amount of 5 mol % to 40 mol %, or anycombination thereof.

Clause 38 of the present disclosure extends to:

The glass composition of any of clauses 29-37, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol % andTiO₂ in the amount of 5 mol % to 15 mol %, P₂O₅ in an amount of 20 mol %to 30 mol %, and R₂O comprises Na₂O in the amount of 5 mol % to 40 mol%, Li₂O in the amount of 5 mol % to 40 mol %, K₂O in the amount of 5 mol% to 40 mol %, or any combination thereof.

Clause 39 of the present disclosure extends to:

The glass composition of any of clauses 29-38, wherein the compositionfurther comprises WO₃ in an amount of 1 mol % to 15 mol %.

Clause 40 of the present disclosure extends to:

The glass composition of clause 1, wherein the composition comprises

-   -   at least one alkaline earth metal oxide (RO) in an amount of 5        mol % to 40 mol %,    -   wherein the glass composition does not include ZnO, B₂O₃, or an        alkali metal oxide (R₂O).

Clause 41 of the present disclosure extends to:

The glass composition of clause 40, wherein the molar ratio of RO/P₂O₅is greater than or equal to 1.

Clause 42 of the present disclosure extends to:

The glass composition of clause 40, wherein the molar ratio of RO/P₂O₅is less than or equal to 1.

Clause 43 of the present disclosure extends to:

The glass composition of any of clauses 40-42, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol % andTiO₂ in the amount of 5 mol % to 15 mol %.

Clause 44 of the present disclosure extends to:

The glass composition of any of clauses 40-43, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 45 of the present disclosure extends to:

The glass composition of any of clauses 40-44, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol %, TiO₂in the amount of 5 mol % to 15 mol %, and P₂O₅ in an amount of 20 mol %to 30 mol %.

Clause 46 of the present disclosure extends to:

The glass composition of any of clauses 40-45, wherein the sum of Nb₂O₅and TiO₂ is 40 mol % to 50 mol %.

Clause 47 of the present disclosure extends to:

The glass composition of any of clauses 40-46, wherein RO comprises BaO,CaO, SrO or any combination thereof.

Clause 48 of the present disclosure extends to:

The glass composition of any of clauses 40-47, wherein RO comprises BaOin the amount of 1 mol % to 25 mol %, CaO in the amount of 1 mol % to 25mol %, SrO in the amount of 1 mol % to 25 mol %, or any combinationthereof.

Clause 49 of the present disclosure extends to:

The glass composition of any of clauses 40-48, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol %, TiO₂in the amount of 5 mol % to 15 mol %, P₂O₅ in an amount of 20 mol % to30 mol %, BaO in the amount of 5 mol % to 20 mol %, CaO in the amount of1 mol % to 10 mol %, and SrO in the amount of 5 mol % to 20 mol %.

Clause 50 of the present disclosure extends to:

A glass composition comprising:

-   -   P₂O₅ in an amount of 20 mol % to 40 mol %;    -   Nb₂O₅ in an amount of 10 mol % to 50 mol %;    -   ZnO in an amount of 0.5 mol % to 20 mol %; and one of the        following:        -   (i) an alkali metal oxide (R₂O) in an amount of 1 mol % to            35 mol %; an alkaline earth metal oxide (RO) in an amount of            5 mol % to 40 mol %,            -   wherein the glass composition does not include B₂O₃;        -   (ii) at least one alkali metal oxide (R₂O) in an amount of 5            mol % to 35 mol %;            -   wherein the glass composition does not include B₂O₃ or                an alkaline earth metal oxide (RO); or        -   (iii) at least one alkaline earth metal oxide (RO) in an            amount of 5 mol % to 40 mol %;            -   wherein the glass composition does not include B₂O₃ or                an alkali metal oxide (R₂O).

Clause 51 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises analkali metal oxide (R₂O) in an amount of 10 mol % to 35 mol %;

an alkaline earth metal oxide (RO) in an amount of 5 mol % to 40 mol %,and wherein the glass composition does not include B₂O₃.

Clause 52 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the amount of RO, theamount of R₂O, and the amount of ZnO sum to 30 mol % to 60 mol %.

Clause 53 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio of(R₂O+RO)/P₂O₅ is greater than or equal to 1.

Clause 54 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio of(R₂O+RO)/P₂O₅ is less than or equal to 1.

Clause 55 of the present disclosure extends to:

The glass composition of clauses 50 or 51, wherein the molar ratio ofR₂O/(R₂O+RO) is greater than 0.25.

Clause 56 of the present disclosure extends to:

The glass composition of any of clauses 51-55, wherein P₂O₅ is in theamount of 25 mol % to 35 mol %.

Clause 57 of the present disclosure extends to:

The glass composition of any of clauses 51-56, wherein Nb₂O₅ is in theamount of 15 mol % to 30 mol %.

Clause 58 of the present disclosure extends to:

The glass composition of any of clauses 51-57, wherein R₂O is Na₂O,Li₂O, K₂O, or any combination thereof.

Clause 59 of the present disclosure extends to:

The glass composition of any of clauses 51-58, wherein R₂O comprisesNa₂O in the amount of 1 mol % to 35 mol %.

Clause 60 of the present disclosure extends to:

The glass composition of any of clauses 51-59, wherein R₂O comprisesLi₂O in the amount of 1 mol % to 15 mol %.

Clause 61 of the present disclosure extends to:

The glass composition of any of clauses 51-60, wherein R₂O comprises K₂Oin the amount of 1 mol % to 10 mol %.

Clause 62 of the present disclosure extends to:

The glass composition of any of clauses 50-61, wherein R₂O comprisesNa₂O in the amount of 1 mol % to 15 mol %, Li₂O in the amount of 1 mol %to 15 mol %, and K₂O in the amount of 1 mol % to 10 mol %.

Clause 63 of the present disclosure extends to:

The glass composition of any of clauses 51-62, wherein RO is CaO, BaO,MgO, SrO, or any combination thereof.

Clause 64 of the present disclosure extends to:

The glass composition of any of clauses 51-63, wherein RO comprises BaOin the amount of 1 mol % to 25 mol %.

Clause 65 of the present disclosure extends to:

The glass composition of any of clauses 51-64, wherein RO comprises CaOin the amount of 1 mol % to 20 mol %.

Clause 66 of the present disclosure extends to:

The glass composition of any of clauses 51-65, wherein RO comprises MgOin the amount of 1 mol % to 15 mol %.

Clause 67 of the present disclosure extends to:

The glass composition of any of clauses 51-66, wherein RO comprises SrOin the amount of 1 mol % to 30 mol %.

Clause 68 of the present disclosure extends to:

The glass composition of any of clauses 51-67, wherein RO comprises BaOin the amount of 1 mol % to 20 mol % and CaO in the amount of 1 mol % to20 mol %.

Clause 69 of the present disclosure extends to:

The glass composition of any of clauses 51-68, wherein RO comprises BaOin the amount of 1 mol % to 20 mol %, CaO in the amount of 1 mol % to 20mol %, and SrO in the amount of 1 mol % to 20 mol %.

Clause 70 of the present disclosure extends to:

The glass composition of any of clauses 51-69, wherein the compositionfurther comprises TiO₂ and/or WO₃, wherein the amount of Nb₂O₅, anamount of TiO₂ and/or an amount WO₃, or any combination thereof, sums to20 mol % to 40 mol %.

Clause 71 of the present disclosure extends to:

The glass composition of any of clauses 51-70, wherein the compositionfurther comprises TiO₂ in an amount of 1 mol % to 30 mol %.

Clause 72 of the present disclosure extends to:

The glass composition of any of clauses 51-71, wherein the compositionfurther comprises WO₃ in an amount of 1 mol % to 15 mol %.

Clause 73 of the present disclosure extends to:

The glass composition of any of clauses 51-72, wherein the compositionfurther comprises Al₂O₃ in an amount of 1 mol % to 5 mol %.

Clause 74 of the present disclosure extends to:

The glass composition of any of clauses 51-73, wherein the compositionfurther comprises CeO₂ in an amount of 0.001 mol % to 1.0 mol %.

Clause 75 of the present disclosure extends to:

The glass composition of any of clauses 51-74, wherein the glasscomposition does not include any of SiO₂, Al₂O₃, MgO, TiO₂.

Clause 76 of the present disclosure extends to:

The glass composition of any of clauses 51-75, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol %, TiO₂in the amount of 5 mol % to 15 mol %, P₂O₅ in an amount of 20 mol % to35 mol %, ZnO in the amount of 1 mol % to 15 mol %, RO in the amount of5 mol % to 40 mol %, where RO is BaO, CaO, SrO, or any combinationthereof, and R₂O in the amount of 1 mol % to 35 mol %, where R₂O isNa₂O, Li₂O, K₂O, or any combination thereof.

Clause 77 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises

-   -   at least one alkali metal oxide (R₂O) in an amount of 5 mol % to        35 mol %;    -   wherein the glass composition does not include B₂O₃ or an        alkaline earth metal oxide (RO).

Clause 78 of the present disclosure extends to:

The glass composition of clause 77, wherein P₂O₅ is in the amount of 25mol % to 35 mol %.

Clause 79 of the present disclosure extends to:

The glass composition of clauses 77 or 78, wherein Nb₂O₅ is in theamount of 15 mol % to 30 mol %.

Clause 80 of the present disclosure extends to:

The glass composition of any of clauses 77-79, wherein R₂O is Na₂O,Li₂O, K₂O, or any combination thereof.

Clause 81 of the present disclosure extends to:

The glass composition of any of clauses 77-80, wherein R₂O comprisesNa₂O in the amount of 1 mol % to 35 mol %.

Clause 82 of the present disclosure extends to:

The glass composition of any of clauses 77-81, wherein R₂O comprisesLi₂O in the amount of 1 mol % to 15 mol %.

Clause 83 of the present disclosure extends to:

The glass composition of any of clauses 77-82, wherein R₂O comprises K₂Oin the amount of 1 mol % to 10 mol %.

Clause 84 of the present disclosure extends to:

The glass composition of any of clauses 77-83, wherein the compositionfurther comprises TiO₂ in an amount of 1 mol % to 30 mol %.

Clause 85 of the present disclosure extends to:

The glass composition of any of clauses 77-84, wherein the compositionfurther comprises WO₃ in an amount of 1 mol % to 15 mol %.

Clause 86 of the present disclosure extends to:

The glass composition of any of clauses 77-85, wherein R₂O comprisesNa₂O in the amount of 1 mol % to 15 mol %, Li₂O in the amount of 1 mol %to 15 mol %, and K₂O in the amount of 1 mol % to 10 mol %.

Clause 87 of the present disclosure extends to:

The glass composition of any of clauses 77-86, wherein the molar ratioof R₂O to P₂O₅ is greater than or equal to 1.

Clause 88 of the present disclosure extends to:

The glass composition of any of clauses 77-87, wherein the molar ratioof R₂O to P₂O₅ is less than or equal to 1.

Clause 89 of the present disclosure extends to:

The glass composition of any of clauses 77-88, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol %, TiO₂in the amount of 5 mol % to 15 mol %, P₂O₅ in an amount of 20 mol % to35 mol %, ZnO in the amount of 1 mol % to 15 mol %, and R₂O in theamount of 1 mol % to 35 mol %, where R₂O is Na₂O, Li₂O, K₂O, or anycombination thereof.

Clause 90 of the present disclosure extends to:

The glass composition of clause 50, wherein the composition comprises

-   -   at least one alkaline earth metal oxide (RO) in an amount of 5        mol % to 40 mol %; and    -   wherein the glass composition does not include B₂O₃ or an alkali        metal oxide (R₂O).

Clause 91 of the present disclosure extends to:

The glass composition of clause 90, wherein P₂O₅ is in the amount of 25mol % to 35 mol %.

Clause 92 of the present disclosure extends to:

The glass composition of clauses 90 or 91, wherein Nb₂O₅ is in theamount of 15 mol % to 30 mol %.

Clause 93 of the present disclosure extends to:

The glass composition of any of clauses 90-92, wherein RO is CaO, BaO,MgO, SrO, or any combination thereof.

Clause 94 of the present disclosure extends to:

The glass composition of any of clauses 90-93, wherein RO comprises BaOin the amount of 1 mol % to 25 mol %.

Clause 95 of the present disclosure extends to:

The glass composition of any of clauses 90-94, wherein RO comprises CaOin the amount of 1 mol % to 20 mol %.

Clause 96 of the present disclosure extends to:

The glass composition of any of clauses 90-95, wherein RO comprises MgOin the amount of 1 mol % to 15 mol %.

Clause 97 of the present disclosure extends to:

The glass composition of any of clauses 90-96, wherein RO comprises SrOin the amount of 1 mol % to 30 mol %.

Clause 98 of the present disclosure extends to:

The glass composition of any of clauses 90-97, wherein RO comprises BaOin the amount of 1 mol % to 20 mol % and CaO in the amount of 1 mol % to20 mol %.

Clause 99 of the present disclosure extends to:

The glass composition of any of clauses 90-98, wherein RO comprises BaOin the amount of 1 mol % to 20 mol %, CaO in the amount of 1 mol % to 20mol %, and SrO in the amount of 1 mol % to 20 mol %.

Clause 100 of the present disclosure extends to:

The glass composition of any of clauses 90-99, wherein the compositionfurther comprises TiO₂ in an amount of 1 mol % to 30 mol %.

Clause 101 of the present disclosure extends to:

The glass composition of any of clauses 90-100, wherein the compositionfurther comprises WO₃ in an amount of 1 mol % to 15 mol %.

Clause 102 of the present disclosure extends to:

The glass composition of any of clauses 90-101, wherein the molar ratioof RO to P₂O₅ is greater than or equal to 1.

Clause 103 of the present disclosure extends to:

The glass composition of any of clauses 90-101, wherein the molar ratioof RO to P₂O₅ is less than or equal to 1.

Clause 104 of the present disclosure extends to:

The glass composition of any of clauses 90-103, wherein the glasscomposition comprises Nb₂O₅ in the amount of 30 mol % to 40 mol %, TiO₂in the amount of 5 mol % to 15 mol %, P₂O₅ in an amount of 20 mol % to35 mol %, ZnO in the amount of 1 mol % to 15 mol %, and RO in the amountof 5 mol % to 40 mol %, where RO is BaO, CaO, SrO, or any combinationthereof.

Clause 105 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a glass thermal stability index of greater than or equalto 200° C.

Clause 106 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a glass thermal stability index of greater than or equalto 225° C.

Clause 107 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a glass thermal stability index of less than zero.

Clause 108 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a refractive index of at least 1.70 at 588 nm at 25° C.

Clause 109 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a refractive index of at least 1.75 at 588 nm at 25° C.

Clause 110 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a refractive index of 1.70 to 2.00 at 588 nm at 25° C.

Clause 111 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a density of less than or equal to 4 g/cm³.

Clause 112 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has an Abbe number of at least 20.

Clause 113 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has an Abbe number of from 20 to 40.

Clause 114 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a coefficient of thermal expansion of from 6.0 ppm/° C.to 12 ppm/° C.

Clause 115 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has an annealing point of 450° C. to 750° C.

Clause 116 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a softening point of 575° C. to 850° C.

Clause 117 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has an internal liquidus temperature of 875° C. to 1,200° C.

Clause 118 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition has a Young's modulus of 50 GPa to 110 GPa.

Clause 119 of the present disclosure extends to:

The glass composition of any of clauses 1-104, wherein the glasscomposition is a glass sheet, powder, bead, fiber, or three-dimensionalscaffold.

An optical article comprising the glass composition of any of clauses1-104.

Throughout this publication, various publications are referenced. Thedisclosures of these publications in their entireties are herebyincorporated by reference into this application in order to more fullydescribe the methods, compositions, and compounds herein.

Various modifications and variations can be made to the materials,methods, and articles described herein. Other aspects of the materials,methods, and articles described herein will be apparent fromconsideration of the specification and practice of the materials,methods, and articles disclosed herein. It is intended that thespecification and examples be considered as exemplary.

What is claimed:
 1. A glass composition comprising: (a) P₂O₅ in anamount of 15 mol % to 40 mol %; and (b) Nb₂O₅ in an amount of 10 mol %to 50 mol %; and (c) TiO₂ in an amount of 15 mol % to 30 mol %; and (d)alkali metal oxide (R₂O) in an amount of 5 mol % to 25 mol %, the alkalimetal oxide (R₂O) comprising at least two of Li₂O, Na₂O, and K₂O, thealkali metal oxide (R₂O) comprising less than 20 mol % Na₂O; and (e)alkaline earth metal oxide (RO) in an amount of 5 mol % to 30 mol %, thealkaline earth metal oxide (RO) comprising at least two of CaO, SrO, andBaO; and wherein the glass composition does not include ZnO and B₂O₃;and wherein the glass composition has a molar ratio of (R₂O+RO)/P₂O₅greater than or equal to
 1. 2. The glass composition of claim 1, whereinthe amount of P₂O₅ is 20 mol % to 30 mol %.
 3. The glass composition ofclaim 1, wherein the amount of Nb₂O₅ is 15 mol % to 25 mol %.
 4. Theglass composition of claim 1, wherein the amount of TiO₂ is 19 mol % to27 mol %.
 5. The glass composition of claim 1, wherein the glasscomposition further comprises WO₃ in an amount of 1 mol % to 15 mol %.6. The glass composition of claim 1, wherein the amount of Nb₂O₅ is 15mol % to 25 mol % and the amount of TiO₂ is 15 mol % to 25 mol %.
 7. Theglass composition of claim 1, wherein the alkaline earth metal oxide(RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in theamount of 1 mol % to 25 mol %.
 8. The glass composition of claim 1,wherein the alkali metal oxide (R₂O) comprises Na₂O in the amount of 1mol % to 15 mol %, Li₂O in the amount of 1 mol % to 15 mol %, and K₂O inthe amount of 1 mol % to 10 mol %, and the alkaline earth metal oxide(RO) comprises BaO in the amount of 1 mol % to 25 mol % and CaO in theamount of 1 mol % to 25 mol %.
 9. The glass composition of claim 1,wherein the glass composition has a refractive index of at least 1.85 at588 nm at 25° C.
 10. The glass composition of claim 1, wherein the glasscomposition has a density of less than or equal to 3.8 g/cm³.
 11. Theglass composition of claim 1, wherein the glass composition has aninternal liquidus temperature of 875° C. to 1,200° C.
 12. A glasscomposition comprising: (a) P₂O₅ in an amount of 15 mol % to 40 mol %;and (b) Nb₂O₅ in an amount of 10 mol % to 50 mol %; and (c) TiO₂ in anamount of 15 mol % to 30 mol %; and (d) alkali metal oxide (R₂O) in anamount of 5 mol % to 25 mol %, the alkali metal oxide (R₂O) comprisingat least one of Li₂O and K₂O in an amount of at least 1 mol %; and (e)alkaline earth metal oxide (RO) in an amount of 5 mol % to 30 mol %, thealkaline earth metal oxide (RO) comprising at least two of CaO, SrO, andBaO; and wherein the glass composition does not include ZnO and B₂O₃;and wherein the glass composition has a molar ratio of (R₂O+RO)/P₂O₅greater than or equal to
 1. 13. The glass composition of claim 12,wherein the amount of P₂O₅ is 20 mol % to 30 mol %.
 14. The glasscomposition of claim 12, wherein the amount of Nb₂O₅ is 15 mol % to 25mol %.
 15. The glass composition of claim 12, wherein the amount of TiO₂is 19 mol % to 27 mol %.
 16. The glass composition of claim 12, whereinthe alkali metal oxide (R₂O) comprises at Li₂O in an amount of at least1 mol % and K₂O in an amount of at least 1 mol %.
 17. The glasscomposition of claim 12, wherein the glass composition further comprisesWO₃ in an amount of 1 mol % to 15 mol %.
 18. The glass composition ofclaim 12, wherein the amount of Nb₂O₅ is 15 mol % to 25 mol % and theamount of TiO₂ is 15 mol % to 25 mol %.
 19. The glass composition ofclaim 12, wherein the alkaline earth metal oxide (RO) comprises BaO inthe amount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25mol %.
 20. The glass composition of claim 12, wherein the alkali metaloxide (R₂O) comprises Na₂O in the amount of 1 mol % to 15 mol %, Li₂O inthe amount of 1 mol % to 15 mol %, and K₂O in the amount of 1 mol % to10 mol %, and the alkaline earth metal oxide (RO) comprises BaO in theamount of 1 mol % to 25 mol % and CaO in the amount of 1 mol % to 25 mol%.